I've got them- and they sound nice to me..... If you've already got the B4, they're an excellent addition-
If you're buying the B4 principally for the extra additional tonewheels, I'd check out the ComboSister from DashSynthesist.com
It's really grand, with a different kind of controls (I haven't mastered b4 programming yet) and a heck of alot cheaper
(wish this woulda been out when shelled out for the B4 AND the extra tonewheels)
Peace
Chris