Out of interest, how many players do you have in your playgroup?

Personally, I think that Star Wars Miniatures can be problematic as a casual game, as there are some components that can be balanced in a tournament but devastating in a one-off casual game - for example, an IG-Lancer powered by GGDAC can demolish an otherwise strong Gungan squad in one activation. While in a tournament, the powerful pieces tend to balance each other out. For example, a year ago, Mace was doing very well in our local tournaments (in New Zealand), but in our tournament on Saturday noone even ran him. I don't think he would have done very well, as among other things there were three IG-88A/IG-88 Assassin droids in the top 8, which Mace would have struggled against. In the same way, there are some v-set pieces like Exar Kun Dark Force Spirit and Admiral Pellaeon that make it much more difficult for the Soresu Style Mastery pieces.

So if you're able to, I think implementing a competitive structure can work well. In New Zealand, Kezzamachine has done a great job of implementing a tournament structure with trophies and rankings. It helps that he's an enthusiastic and charismatic leader, but he had 18 of us at LowerHuttACon this weekend, all enthusiastically trying to play competitive squads. Out of interest too, the winning squad was almost entirely wotc pieces - the squad relied on the game controlling abilities of Thrawn, Ozzel's activation control, and Cad Bane's finishing power.

That's just one way to go, but it works well for us in New Zealand! Your idea of at least using some v-set pieces sounds great to me - I think it's good to have some new pieces to keep things fresh.

Without the V-sets though, Wizards wound up bottle-necking the meta down to a half-dozen squad archetypes at best, and with that little variety, the competitive scene would've stagnated and died if not for the V-sets.

To the OP, I think it's great that you guys are starting to allow some V-Set pieces into your games! If nothing else, they'll bring variety. I think you'll find that several of the V-Set pieces also help to bring older and un-used WotC pieces back into play (Sevrance Tann for huge figs, Jan ors for the old 31pt Kyle Katarn, etc).

I just want to suggest an alternative to banning a certain piece: houserule it instead.
--Is Mace a problem? Then I'd suggest dropping Flurry and see how he works.
--You hate Zannah? Then maybe remove her Force Bubble and Lightsaber Combat Expert...she's fine after you do that.
That's one of the great things about local play groups: you can houserule anything to make it more palatable for your players.

I would definitely advise caution when it comes to houseruling game mechanics, but for specific individual pieces you can't really go wrong with houserules. If a certain houserule works well, then you've opened doors; if it still needs to be tweaked after a few matches, then so be it.

This is the plan. There are a lot of V-Set pieces, which even *I* would argue are neat, but it's hard to just 'play V-Set' when you have some broken pieces - and there are broken pieces - running around.

We're going to take Mace's Flurry and triple damage away.
We're going to simply ban Darth Z.

I mean, what choice do we have? We've been playing completely vanilla, which to me has been great, but there are players in our group itching for V-Set again, and I have to throw them a bone at some point.