Classe CP50 or Sim Audio???

I'm considering picking up one of these. Can anyone describe the relative differences between the CP50 and the Sim P-3 or the Celeste P-5003 predecessor?

Buying 2nd hand It's a little difficult to demo. From what I've been able to read, I'm thinking the Sim Audio may be a little more polite and layed back. I don't want something overly smooth. I know this is also system dependent but any feed back would be appreciated.

Thank in advance.
As you put it, synergy is going to answer the question, so what's the rest of your system like. I've never owned sim but have heard a lot, and never found it to be polite or layed back, but I've heard it mostly with totem and triangle, so it's come across as rhythmically correct and very well paced/coherent through the mids, with a snappy lower end. This sound appeals to some (def. to me) and is more associated with the synergy of the sim/totem matching than just sim itself. I've heard some classe and always enjoyed it, but think the sim is a more special sound, imho. Now this also depends on your gear, so what else is going with it?
To drive the "system dependant" point further, I have had the opposite experience of Mimberman. I have not compared the CP50 and the P3 directly but I owned the former and know the latter. I find the Classe to have a special sound - rather smooth but with incredible inner detail, not very laid back but not forward, very musical and highly varied timbre. The Sim system was a little leaner - I don't feel comfortable saying anymore since the comparisons weren't head to head. both are excellent though.

What is the rest of you gear? Arthur