McIntosh MC275 MK IV vs. MC402 / MC352

Hi everyone, 
I need your opinion on a tough decision. I currently own an MC352 and an MC275 MK IV. I run the MC352 most of the time for home theater and music, and the MC275 every few days, purely for stereo listening. My speakers are McIntosh XRT28's which I'm taking with me to the grave. I love the bass punch of the MC352 and the overall pure power of it, especially for rock music though I do fee sometimes that vocals a little less neutral, in comparison with the MC275. As far as the MC275 and the XRT28's -  beautiful highs, dreamy mid and low and welcoming bass (no punch). I've received an offer to trade my MC275 for an MC402. That way I can either bi-amp my speaker with both the MC352 and MC402, or use the the MC402 for fronts and MC352 for backs.
My questions are - regarding of value - would you make that trade? Does the MC402 sound more natural and more "tubey" than the MC352? or should I keep my system as is - SS for everyday, Tube for the special occasion.
Thank you!

Yes, keep your system, SS for everyday and Tube for special occasion.

IMHO, frequently resort to entertaining upgrades that may not necessarily "improve" the system's performance, but do create detectable changes in the performance. However these artifact styled "improvements" become boring after a while, because they add the same accent to all music, making it sonically one-dimensional.

I did upgrade from one MC275 to two and now MC601 Mono Block, I kept both amp to enjoy the experience of their difference.

Beewax - I think that's a great direction. I can keep my eyes out for another MC275, and eventually (once I get a bigger house) move to two MC501's or MC602. Do you run the same speakers with your setup, just switching between the amps?
I just switched the amps when I get tired of the same sound. I also rotate frequently between music server, turntable, streaming and cd player for different music experience and enjoyment.
I have a MC275 GG commerative edition in storage, I have never played it as of yet. I am interested to know if I am missing anything by not using it. I have an MC2102 that I used to use more often but my understanding was that the 2102 was maybe a little step ahead of the 275? I regularly use my 501's. I have been thinking about selling either the MC2012 or the MC275 but for some reason I haven't been able to been able to part with them!