Bass Management

First, I'm currious as to "why you would want to run the powered mains as small and the rears as full range?" If anything, you should(assuming the mains are a full range speaker with powered woofers) run the mains as "large" and the rears(passive full range towers) as small! The powered toweres do a much much better job of handling "full range" than the passive rears!!! Unless the rears are ULTRA HIGH SENSITIVITY AND EFFICIENCY, this is definitely NOT AS DESIREABLE!(POWERED SUBS DO BETTER HANDLING DD/DTS BASS!).
BTW, how low do the AR1's play and how big are the bass drivers?...this makes a difference in how you might consider crossing them over, if at all.
Worse case scanario, I would run all the speakers as "small" and add a powered sub(s). You could to "full range" to all the speakers if the mains are large enough with big powered woofers. Normally, there's not so much bass info at the rears to sweat it that much if push comes to shove(although not ideal in my experience). Then again you could consider changing your reciever(which is always going to have less current capability to do proper justice to MOST ANY SPEAKER FULL RANGE FOR DD/DTS!(except powered speakers, or running "small + sub"). The possible exception is when you're running speakers that have very very high sensitivity ratings, like 96db+!

Bass management, If any for sacd along with dvd-audio would be in the player itself. Your receiver bass management is for DD&DTS. Music surround setup is a little different than for movie surround. I would only use monopole or bipole speakers for rears in a music set up. Also a lot of the pop and rock music that is out has deep bass in the rears as well as the fronts. It is not ment to be defuse sound as in movies (try Frankie goes to hollywood) and you'll hear what I mean, Also Pink Floyd dark side of the moon will be out soon as will lots of other stuff of this nature. If your player does not have good bass management or none at all then go to outlawaudio.com and get their ICBM, it is a bass management device that works very well, I think it sells for about $250. If you have full range speakers I would use them that way for multichannel music. Also it is much more important to have a very high quality center channel for music than it it for movies as a lot of recordings use the center for vocal only. Hope this helps.

(SoGood51)...With most receiver set up's there is no way to add the ICBM from OUtlaw to the system to all channels! Unless the receiver has "pre-out's" and "main-in's", you can't do this. If he was using pre-out's to another amplifier or something, he could indeed buy the Outlaw ICBM, and configure as he pleased using that device(simply setting the receiver to "large" for all speakers). But that's not the case from what's in question here I think.