I've made several progressive upgrades in my HT involving different power amps, amps from different manufacturers, etc. Yes, I agree with the logic, the rears would seem to need less power. That said, logic isn't always true.
I have used higher powered amps for my fronts, mainly to improve two channel listening, but the difference wasn't huge (250 wpc vs 200 wpc)and it's worked well.
I've found several problems in using different powered amps on fronts/rears.
1) If using amps from different manufacturers, or even different lines from the same manufacturer (ie Aragon/Acurus) you may find that they respond differently to the various pre-amp out levels. This makes balancing the surrounds MUCH more difficult than just adjusting the output levels on the pre/pro. You will need to adjust the pre/pro for EACH different volume level, so forget about getting the balance correct throughout any entire movie! This can be a problem if the different amps can't 'perform as needed'. If you're using different manufacturers amps, timbre can also be a problem, even with similar speakers, causing apparent balance problems.(That said a very good friend of mine has ML/Proceed amps in his HT and they seem to blend perfectly!)
2) If you're using different speaker for the surrounds, a similar problem can arise, this time caused by the speakers themselves due to their intrinsic response to different amp output or different frequency response causing 'apparent balance problems' (sorry, I like that phrase!)
These two problems have been the reason I've headed to a proprietary system for my HT. Despite all my playing with different companies, I found it easiest, and sonically best, to pick a speaker system I liked and get it, pick an amp system I liked, and get it. This has really improved the balance tremendously!
From my listening to many friends systems, I would highly recomend this tactic. The differences can be subtle at times, but I notice them, the guests may not but........
This would also coincide with Sutts system. In HT, timbre, response, speaker placement etc. are all significant variables, minimizing as many as possible will make your system easier, and more enjoyable to use.
Just my .02