I own two C-5s, have for 2 years now. I like them a lot. For the price I couldn't find anything I liked better. If I'd had another 400 dollars at the time I probebly would have gone to another brand but for the price I think the C-5s sound wonderful. I've built a whole home theatre around them since with other C-series speakers from Energy.
I don't know the rotel receiver so my point here was just to say I like the C-5s. Just FYI, I'm using NAD amps.
Energy recently gave me outstanding customer service (a favour really) and I was very impressed by that.
Do audition other speakers though and go to more than one hi-fi shop too. But yes, the C5s are nice.