So, I put a lot of time on the machine last night and am now a huge fan of A1Up's SW and Marvel stock tables. From what all I played, they play smooth and responsive, with only the slightest of flipper lag. I think if I had purchased one of these tables initially, it wouldn't have left me with such a bad taste as did the Williams package.
Goings back to the William's package, there's still some tables that struggle, The Getaway was the most notable for me, where it's pretty laggy (even with all special visual settings turned off). The plunger issue also still exists on TOTAN, where it's way too powerful for that skill shot (I also found that those skill shot targets don't always award the shot when made). NGG and WH20 play much better now, but NGG still has some odd ball movements from time to time. As a whole package, though, these tables are much less polished in comparison to the other A1Up packages, and I hope they get more refinement with future updates (although, I'm doubtful that will happen due to A1Up's track record with continual updates). Regardless, each table is now playable, for the most part, so thanks to A1Up for making that happen!
As for the "secret" Zen tables, this is an awesome addition. It is still buggy, occasionally crashes, and navigating the menus takes time to get used to, but this is off to a great start. Looking forward to what's to come on this!
As for my gripe about that dang flipper-to-rest sound, now that I've spent much more time tweaking settings, I've upped the music and sfx volume which now drowns out that annoying sound, yet ball colliding sounds and other important physics effects can still be heard prominently.