Steak, welcome. As to basic sound quality viewed strictly as an amplifier(no processing features taken into account), there's no need for concern about any well-designed modern HT receiver. They amplify transparently within their designed maximum power limits without adding an audible sonic coloration. Any amplifier that has a "sound" is either incompetently designed or defective.
Amplification should not be bought by the pound; if the desired power capacity is supplied, the weight of the units doing so can vary widely, depending on design, without significant effect.
For more up-to-date features, including most significantly Audyssey MultEQ XT auto-calibration and room correction, I'd suggest that you consider(especially if you still want to consider the weight factor)the factory refurbished(which should be, if anything, even more reliable than a brand-new unit)Onkyo 809 from Accessories4less here
, a great bargain at about $600. The 709, with a slightly lower maximum power capacity, is an even better bargain there at around $430.