So when people say that Giffen hated Karate Kid or Sun Boy, I often think that Keith Giffen liked Shrinking Violet. She's a character though, that I don't think often gets her due, for several reasons.
A "shrinking violet" is an extremely shy person, which is somewhat how Salu Digby was presented, with the play on words that she had the power to shrink. Like Sue Richards, her power was basically to disappear out of sight. She failed her first attempt at Legion membership. She was a member of the Espionage Squad and some classic stories even showed her being strategic on her own, as when she basically beat Grimbor and Charma by herself. That's a story that showed her being very useful in the beginning by investigating the locks on the shackles for Superboy and Timber Wolf.
As most people know, Vi was captured and impersonated by Yera, who later became Chameleon Girl. This experience changed her. It hardened her to an extent. Her personality sorta goes all over the place until she and Lightning Lass start bonding. Shrinking Violet did need some work as a character, it's just a shame that most of the missions we see her on, it is actually Yera.
Vi became a key member of the 5YL for which I think Giffen may have had some hand in. She had some significant storylines in the Reboot. We didn't see much of her Threeboot counterpart, Atom Girl, but she did have some interesting moments. We didn't get much of Shrinking Violet throughout the Retroboot either. Her only big win is in the v6 annual where she defeats the Emerald Eye. That issue was co-written by Keith Giffen. And the Bendis Legion version didn't even utter one word balloon. I think it's safe to say, Vi often ends up being a somewhat ignored Legionnaire. I have to ask myself why.
COMPARISONS
There are a fair amount of shrinking characters between Marvel and DC. DC had the Doll Man, Atom, Blue Jay, Elasti-Girl and Bumblebee. Marvel had a few Ant-Men, Wasp, Yellowjacket (the female one), Stature, Thumbelina and Micromax. There are probably a few others I'm missing. The one thing to note is many of these characters were scientists. Many of them could grow as well as shrink. Some could fly. And some of them had other gimmicks as well, like energy blasts.
So what does Vi have? Well, she is not a scientist. She can fly via her flight ring, but so can all the other Legionnaires. Shrinking Violet temporarily gained the power to grow from Thora in Adventure 368. Reboot Vi was granted the power to grow permanently. And I'm not sure we ever saw LeViathan shrinking much after that.
The reality is Shrinking Violet doesn't have anything power-wise that sets her apart. She has to rely on hand-to-hand combat, though I feel it may just be laziness or a lack of proper scripting that doesn't show Vi using her powers in battle.
DURLANS
I'm not sure when the first time Chameleon Boy assumed the form of a small insect. Durlans don't seem to have a lot of mass restrictions for their shape changing, which means they can become a large beast or become the size of a fly. They can basically approximate Violet's powers for all intents and purposes. We even saw in the Retroboot that Durlans can copy the powers people in their proximity. Side note: I don't think Durlans need to be that powerful. Nevertheless, it appears that Cham could not go subatomic without Vi present, in v7 when they enter Validus's prison cell. But with Cham, he is also the Legion detective and a lateral thinker. When they are both in a story together, he ends up getting the spotlight over her, even though she has shown detective skills as well. But as stated previously, Durlans shrink enough not to cause suspicion that Yera was impersonating Vi. Anything Vi can do, Cham can do better?
POTENTIAL
Vi certainly had some battle prowess. She was noted for it even in the Reboot. Remember how I said she delivered the victory against Grimbor and Charma? Consider this page:
Really, you can't do much better than this for solving a problem. To me, it's no surprise that this character later became leader of the Legion at the tail end of the 5YL run. The only problem is so many Legionnaires also show similar potential for leading squads or teams. In fact, Tinya was the deputy leader of the Espionage Squad, not Vi.
RELEVANT?
Shrinking Violet has what I like to call a 20th century power. What I mean, is that during the 20th century, it works well for different things but doesn't hold us so well in future stories. Anyone who watches Star Trek (24th century) knows how their computers can scan for life signs on a ship or planet. Scanners would likely be able to detect an Imskian infiltrator. I would assume anyone who watches any sci-fi would think similarly of the 31st century. This is where the hard truth comes in that if you view the Legion as a sci-fantasy book, it's really hard to make her useful in a battle scenario against star ships or multiple enemies. Shrinkers can be useful, but they are only good for one enemy at a time, whereas someone like Shadow Lass may be able to crowd control several opponents while another Legionnaire attacks. It was the Atom's intelligence, coupled with his shrinking power, that allowed him to defeat Darkseid. However, to make another shrinking character a genius is about as inspired as making your electrical characters also Black.
Vi is the only Legionnaire that can go subatomic. But how often does a superteam need that particular skill set? Not often. Also, with the 31st century, once can presume nanotech becomes more and more advanced. You don't need a shrinker to enter into someone's bloodstream to do something.
THE POWERS
As Atom Girl, Salu had access to dual pistols.
She was the only Threeboot Legionnaire who regularly carried weapons. It may have had something to do with her being in some microverse. I don't have a problem necessarily with Legionnaires using weapons; it is nicer though when the weapons work with their power in some fashion. However, having any type of blaster will immediately draw comparisons to Wasp. This scene does give me something to ponder.
We don't know much about how Shrinking Violet's powers work. Adaptation to pulsating world? I think we need to scrap that origin. The Threeboot almost hints at a connection with Brainiac shrinking technology. What we see in these panels is the guns shrink and grow with Atom Girl. Obviously, her flight ring and costume always shrank and grew with her. Perhaps she does have the ability to cause objects in her immediate possession to shrink and grow with her. We are going a little into Pym territory with that power but she would have the limitation that she can't increase the size of an object past its original size, whereas Ant-Man and Wasp in their movie would use Pym particles to grow objects to a larger size. The downside to shrinking enemies though is that no one else would be able to fight them, so maybe it's not super useful.
Ray Palmer was able to assert some control over his mass so he could hit harder. Coupling that with her flight ring could make Vi a much harder hitter against an enemy. I fear that's also an easy one to give to a Durlan too.
There isn't a rule that she couldn't have some sort of microscopic vision. If you don't have Sensor Girl in the Legion, it's not going to hurt having another character with some enhanced vision powers. You have to figure, once she shrinks, her eyes can't perceive light the same way. Electron microscopes don't work on light. Microscopic vision could also play into her being a bit more of a detective as well.
Is that enough? The strength of the Legion has usually been its members with "quiet" superpowers though that is when the stories give them a chance to shine.
THE FUTURE
Shrinking Violet has not played a part in Bendis's Legion. He seemed more focused on certain characters. It remains to be seen if he will give some time to some other characters. I do wonder what the point of including her is if you don't do anything with her. I know Bendis doesn't care about that stuff and thinks we should either.