Hawk, it's all very puzzling, however, as soon as I read in your post that it's a "great room", with cathedral ceiling and that you and your wife "like it loud", I thought, oh-oh, he's had the VP-150 set to "Large" and he's clipped the H/K receiver and burned out the drivers.
Drivers don't "just wear out". They'll go on working for 20 to 30 years so long as they're not overdriven with an amplifier that's clipping or unless there's an original manufacturing defect. In the latter case, they'll fail very quickly. Crossovers are rarely defective, although a cold solder joint or cracked circuit board could be the problem, and that would be hard to see or detect.
Given the size of the room, and your listening tastes (loud), an M2 center (per JohnK) would be totally inadequate. I'd suggest at least a new VP150 or, the VP180.
As to audible differences in your VP150 and the v3 version, they'd be subtle and wouldn't be a problem in terms of tonal matching to your existing M22s.
Regards,
Alan
