Difference between these two...cart & developer

I am a newbie starting an online triathlon store similar to sbrshop.com and trisports.com. I was considering going with a yahoo store developer and then I discovered these shopping carts which I assume is pretty much the same. Could someone help me out and tell me what the difference is between the following two.

http://www.1choice4yourstore.com/yadesppl.html

or

Volusion.

It looks like 1 Choice give me a lot of features but I do know they write in RTML which means I am kinda locked into there store....I guess.

Thanks for any input.