If the OP's issue is paying for the extra channels, I kinda get it. The good news is that - presumably - the bulk of the cost associated with "unwanted" channels fall to the power amplification - particularly if you're looking at equipment with a reasonably high quality power amp section.
Once you go with separates, the problem largely goes away. I just bought a 9.2 channel pre-pro for use exclusively with a 2 channel amp in a music only 2.2 system.
My advice to the OP would be to do the same thing I did. Accept the extra channels on the pre-pro, buy but a 5 channel (in this case) power amp.
I have no experience with/opinion on the Emotiva, but am very happy with the Onkyo I bought.