The 663 is probably the cheapest new thing you can buy to act as HT pre/pro, with advanced codec support. It has numerous limitations, but then again none of them might bother you in the slightest. The one that really bothers ME is that it cannot matrix advanced HT bitstreams, as I am a 7.1 user.
Also, I would really consider spending about $100-150 more for an Onkyo 705, if only for Audyssey XT. XT has at least 8x the filtering resolution of the vanilla MultiEQ.
The newer xx6 models seem to have downgraded to normal MEQ, but offer dynamic EQ as well.
If you have an acoustically challenged room, or are free to have it as loud as you want, whenever you want, go for XT.
If you share walls with neighbors, or have sleeping kids, go for Dyn EQ.
Some folks do not like these room correction systems. I think they are the coolest thing since sliced bread.
I love XT so much, that I was searching for something like that for my 2ch stereo. The economies of scale perhaps disallow smaller 2ch companies from implementing them. The stand alone Audyssey SEQ is about $2k. With that in mind, XT for $450 or so is quite the bargain IMO. The next step above XT is Pro version, which requires a professional to calibrate, along with associated fees. The versions below XT are MEQ and 2EQ.
and besides, the 705 would also allow more flexible bass mgmt, matrixing of bitstreams, more HDMI inputs, among other things I've probably forgotten.
Good luck.