I have the pioneer sc-lx81 and I would say it was not as bright as say the pioneer vsx-lx70.
The bass is definetely not as loose. and being THX ultra 2 plus you are defintely getting an amp that should suit most systems.
There should be a lot of control there.
I would definetley say avoid the pioneer sc-lx72.
I would demo with lots of different discs and at quite loud volumes.
Pioneer Sc-lx81, Pioneer Bdp-lx71, B&W FPM6 x 2 on floor stands, B&W FPM5 on table stand,
B&W FPM4 x 2 on floor stands, B&W PV1, Philips 32PF9731d Lcd, Optimum AV300, Chord Silver HDMI x 2, QED Silver Anniversary XT.