Rear speakers and receiver crossover....

[wem003]

I've searched the forums, and can't find a post that really nails this answer for me - so here it goes...

I am using an Onkyo 702, have 2 Era Design 4's for the front, and and a Design 4 LCR for the center.

I have two Design 3's for the rears.

The D4's sound amazing with my crossover set at 60hz. (I rarely use a sub since my movie room is right next to the kids rooms. So at night, I am a low volume watcher.)

My question is about what kinds of frequency ranges can get sent to the rears? Since the D3's need a crossover closer to 80hz, should I have the receiver set to that? Or do the rear channel effects never really approach what comes out of the front?

Sorry for the noob question - but its just not clear to me how critical it is to match specs for the front and rear channels as long as the speakers are voice matched.