Actually I have a D2 Carbon helmet. Well I didn’t die, dually thanks to the comments on here. The class was very good, the instructor didn’t have us doing stupid stuff, the crank arms were much shorter than on my bike, so I felt I was riding a kids bike, but all in all, I sweated a small child out, but did enjoy it, even with getting cramp half an hour into the 45 minutes class. But I battled on. And yes, there were people there that did not break sweat.
Thanks for all the comments folks.