I think most any 12-channel amp would work fine, as far as sound goes. Almost all multichannel distributed audio amps are digital, nowadays.
Are there any bells or whistles needed on the amp, for use with the C4 system? Looking at one the Episode multichannel amp webpages, I see at least one offers 'audio-sensing', and has a 12V trigger. If those will be needed, and you're buying a different one, you need to do some homework.
Niles, Speakercraft, Sonance, HTD, Elan, Dayton Audio - and many more.
I think Episode is fine, and easy - no hassles. If it doesn't work, the installer is responsible for troubleshooting, fixing, and replacing. I would say that's worth a premium.