If you do a search on the Axiom and Ascend boards, you will see that M22's and CBM-170's (old and new) have been compared a fair amount. There are comparisons on the AV123 board as well.
If you are going to make a change, then I suggest making a bigger one. Like jc posted, go tot he CMT-340SE, or the M60's. From AV123, I would skip the X-LS Encore, and go to something bigger as well.