I'm just afraid of my CC charging me a cash advance fee. I guess I can try a small transaction and see how it works.
Try with small amount(s). Like $50 or so. You cannot be charged much.
I've been using other website that can do this too, and I was like you. So I gone small, $20 first time. After that was fine and I was charged about 0.7% I gone with $50. It was the same. So you can try with small amount without fear.