Jason,
I'm afraid I'm one of those sticks in the mud who believes in the theory of an "unbalanced" Home Theater system.
The (usual) function of rear speakers is to produce localized "effects" for movies (wind/rain, explosions/gunfire, animals in a forest, etc). If the quality of sound (from your rear speakers) is not absolutely true to the source, what is the ramification? Very little, if anything.
I mean if the movie is depicting someone mowing the grass behind you, and that person is using a Honda lawnmower, but my "inaccurate rear amp" causes it to sound like a Lawn-Boy, I mean who's going to care??!?? If someone is firing an American made machine gun, but my "underpriced rear amp" is causing it to sound Russian made, I know I'm not going to notice. I'm just enjoying the movie. Remember, we're talking effects here, not the nuances of a flute solo.
As long as the amp and speakers match up, and they are capable of playing at a decent volume without breaking up, I feel certain few will notice the difference. And my opinion is that you can get well above this minimum level of performance (for rear speakers) for less than $1,500 for a multi-channel amp.
My advice is ALWAYS to spend the main bulk of your HT cash on 2-channel playback (which will also serve as the main speakers in your HT). The next largest percentage is for Subwoofer and Center (if you use them). And finally for pre/pro/receiver and surrounds.
So, if someone has $9,000 to spend on amps, my advice is to spend $4,500 on stereo monoblocks, $3,000 on stereo preamp, and $1,500 on a 7.1 Receiver (with pre-outs).
The same goes for $9,000 worth of speakers: $6,500 for stereo mains, $750 for Center, $750 for subwoofer, and $1,000 for 4 surrounds.
The exception to this is the person who hates music - will never own a CD - and would execute anyone who ever tried to play music through their HT system. For everyone else, my system allows excellent HT reproduction (maybe not quite as good as a "balanced system" in every possible application). But it allows for an "Oh my God" type of 2-channel music reproduction when that mood strikes.
I know this is not the normal opinion espoused on these types of sites, but you asked for input... and I feel very strongly in this approach to Home Theater setup.
Kevin