I have heard the C2 and the Temptation. Both wonderful products. So is the Special 25, which I own. Before even considering upgrading speakers you should look at upgrading your source and amplification of your Special 25's. Though they may sound nice, you are only getting a fraction of what they are capable of with your current system. I don't think the power of amplification is nearly as important as quality, and I am of the source importance school of thought as well. I would look at shopping for electronics first, listen to the 25's as they develope and keep a mind to upgrade of speakers. I use the Belles Ref150A power amp with that in mind as I may go to the C2 in a few years and will then set them up as mono amps.
If your looking for better sound, I don't think that your speakers are the weak link. David.