I've hadn't heard of them until you mentioned them, so I can't offer any input about them. I do prefer to buy from sites that offer detailed "about us" and contact info including a physical address and a phone number. Granted, that info can be faked but I'd call them to make sure they sound legit. I have ordered from importgsm.com and expansys-usa.com, and I know first hand that those are reputable sites from which to buy import phones.
The Hero has HTC's Sense UI while the magic is vanilla Android. I'd definitely go for the Hero, though both are nice phones. That is, unless you need T-Mobile US 3G, in which case you'd want to go with the Magic that has the 1700/2100MHz 3G bands.