One thing to remember about Home Theater is that there really is no 'reference' standard. Unless you have precisely the same speakers for Left, Center, and Right, channels your center channel will sound different than the others. In home theater, much of the sound comes out of the center channel, so you might want to upgrade your front three channel amplification (just a thought).
The other thing about home theater is that DVD recordings/sonics are not that good when compared to two channel audiophile recordings. Having speakers that are matched gets you 98% of the way there for good home theater balanced sound. Amplification is almost a secondary concern per se. What a better 2 channel amp will give you that you probably will notice is better bass response in the front two channels. I run 7.0 channel sound with my two channel system driving the L and R channel. My L, R, and C channels are all matched (Vienna Acoustic); however, my rears and sides are from a different speaker manufacturer altogether (Acarian Alon). The sound still is truly amazing. My L and R speakers play so low (22hz) that I have no need for a sub.
If you want a large leap in performance from your Rotel without breaking extreme budget, I would suggest going with something like an Aragon 3 channel amp used. Another option that could be very good would to be going with Monarchy SE100 monoblocks. I once drove a complete HT system with Monarchy monoblocks. These little amps sound awesome and are very good deals used.
There are a lot of ways one can go with amplification.
What I would not worry about is the different amplifiers driving your speakers. YOu have matches speakers, and that is 98% of the battle.
KF