B&W upgrade

I own a pair of CDM7SE's, the CDMSE center channel, and 601S2 for my rear. I was thinking of upgrading the 7SE's to the Naut 804's. Would this be a good upgrade. Would the CDM7SE work for the rear. I need equipment advice also please, I only have a Harman Kardon AVR65 pushing them.
I have the CDM1SEs and love their sound. I've also heard the 805s, 804s, 802s and 801s. My impression as you move up the ladder is that the B&W "sound" remains, but there is just more of everything! Wish I was in your position to consider an upgrade, but for now I'm very satisfied. As far as amplification, I found that running the speakers with more than rec'd power is an improvement(as long as you don't damage them--I don't mean to lead someone into a disaster). The CDM1SEs rate at up to 120watts, i believe, but I use McCormack's DNA-1 (150watts @8ohms) and it really makes them lively. Of course, this is 2channel, and I don't know much about amps to rec for HT. best of luck.
In my experience, I feel that B&W's sound better when run with a little more than adequate power. My 804 matrix are run by a Bryston 4b, although a 7b wouldn't hurt. As for the Nautilus series, I have heard the 805's run by a FPB200 and they sounded tremendous; I can only imagine how the 804's sound.