WoW! Sorry I couldn't email you guys back...been really busy at the retreat, these things are more popular than I had though...here is some more info you wanted.
Carbon and Ceramic are the infrared heaters used to heat the sauna. The carbon heaters penetrate deeper into your body to detox you and heal you. Ceramic heaters are the older technology and are cheaper to make. Also, they have to get so hot to keep up that they can lightly burn your back it you sit right against them(like a sunburn)...Carbon Based Heaters won't do this. I know because I sit against them for an hour a night an read...feels great.
I'm not sure where you would try one unless you want to fly to Colorado and try mine :-), but personally I would just pull the trigger and buy one. You won't feel much during your first session, it's after about the 5th session that your body opens up and really starts to detox and sweat the metals out. I know you may be a little sceptical about the investment but I absolutely LOVE mine and use it every night. It did wonders for my skin as well.
Email me with any other questions. I bought mine from Coastal Saunas http://www.coastalsaunas.com
which carries really nice carbon based models. By the way, I searched for 6 months and this is the best one I found...the other companies have the cheap ceramic heaters for the same price. If you call them talk with Tim, he is the VP of the company and is mostly interested in educating you rather than giving you some sales pitch, it's 1-800-327-5122, very friendly...tell him I recommended you :-) and maybe he'll give yo the same deal.