Thanks folks for your explanations about the wheels. Ah, cool, I watched the videos and that has cleared things up regarding tubeless clincher. That seems really compelling, not having to use tubes and also not having to glue on a tire. It looks like this kind of rim has been out for a few years and looking at tires, I'm guessing this kind of wheel and tire set up hasn't exploded in popularity. I think I'll wait for it to become more popular, as I'd hate to go this route and then not be able to buy tires anymore a few years down the road.

Also, thanks for the suggestion about the RS80 being the same rim as the 7900 set. That's good enough for me and being about the same price as the Easton set, I'm more inclined to go with Shimano. Ouch, shipping from Ribble seems expensive but I guess the prices they have are pretty good. Thanks again everyone with your opinions and explanations.