Well.... The rear speakers are going to make much of a difference, except for being louder. Definately not good when focusing on SQ. But.... if you tune the amp right, you should be alright.
And... if your going for SQ, I'd definately consider something else other than the RF. Lots of power, but a bit more distortion than I would like to see. I know a guy, locally, thats selling a couple 4 channels, one'* Eclipse, the other I forget, but both great amps, dirt cheap too.
I don't like Titanium tweeters myself, a bit too sharp. I'd consider silk for a bit softer sound.
2000 Bonneville SE