Yours is the perfect question for the man who designed and built these two units. Please visit the link I have provided below, and ask Mike Elliott.
I had a SA-12 upgraded to a SA-100 and the sound was less warm IMO. Because Counterpoint has such a forward sound in the mids, you really need top equipment and cables or it will sound etched in the mids.
I have not heard Classe often, but I believe the Classe would be warmer sounding.
However, if you have speakers with great resolving power in the mids, you might like the Counterpoint. I used it with Vandersteen 3a's(not the signiture) and they didn't have the midrange clarity and didn't match well.
I now have Avalon Arcus and it probably would have matched up better with the Counterpoint.
I had a Counterpoint SA100 (now completely upgraded and rebuilt by Mike Elliott) and I didn't find the mids to be too forward or etched. In fact, I preferred it to everything I compared it to...an old Luxman amp, a Bel Canto SETi40, an Aleph 3, and a 47labs GainCard (all made with a Pass Aleph P, Merlin VSM-SE's and Cardas Golden Cross cables). Of course sound is subjective, and I have never tried it on cheaper equipment.
I would follow Albert's advice and ask Mike about the two units. There is one disadvantage with both...they both have mosfets that can go bad. Mine were fine, but some people do have problems. If they do go, they might be a little pricey to fix (so don't pay too much for the used amp). I'm sure Mike can tell you all about that too.
Besides all of the above...the SA amps are hybrid designs with four tubes. There is a good degree of tweaking that can be done by changing tubes. I went from the originals to Tesla's to Mullards and there was a pretty significant difference. They really are a great amp for the money if you can find one in good shape, for a good price.
My (limited) first hand experience with Counterpoint gear is that it is not "warm" at all. I find it to be pretty forward sounding while offering bloated, indistinct bass. Others that i know and trust have said that they found the Counterpoint "hybrid" amps to offer the worst of both SS / Tube worlds. Then again, audio is VERY subjective and everbody obviously has different tastes / system goals. I think that this is one brand of gear that falls into the "love it / hate it" pile. Sean