It's not a bad idea! And there I get my money back if they screw? Please help me because I do not know how to operate such a service ...
That's only IF they were willing to work with an escrow, which I doubt.
Since you said that they are actively replying to emails, then you could probably just ask them directly if they're willing to work with an escrow or something.
Anyway, you seem decided to try them out. Consider also that, your "small amounts" may work fine for some time but soon as you hit a "certain amount", things may not work so well.