I've never had a problem with Billy's playing or sound. I never heard him in Talas. He does go crazy and play more of a "lead bass" in PSMS or, say, Vai solo stuff. But not in more "straightforward" rock. While still definitely "flashy," I never really felt like he was taking over in Mr. Big, DLR, or Winery Dogs. I'm not saying others can't feel that way, or that you can't feel like his style just doesn't suit you. Just saying, it never really stood at to me as a problem. And if he were to be in this project, I'm not sure his flashy, sometimes over the top style is out of place in a genre where bands do things like having three bassists and a "lead bass" approach. Heck, look at JM's approach in the Majesty/WDADU days.
That said, it doesn't seem like he is involved in this, which is fine. I know for me, I would prefer him to NOT be involved. But that isn't necessarily because of his playing. Hopefully, Mike has put together a lineup and will help guide the writing of the songs such that the players compliment each other and nobody's particular playing style detracts. For me, my reasoning is simply because he has recently worked on two projects with Billy, and adding Billy to yet another project would just feel to me a bit incestuous and like he cannot break out of the usual cast of characters. But we'll see. I'm optimistic, and I hope the music lives up to the hype.