You're probably making a huge mistake if you order from Xhash... or from any company that doesn't have an active thread in the Hardware subforum.
Please do your research or you WILL get burned.
+1 to this.
Many manufacturers send Dogie a sample unit for review. Also if ckolivas and luke-jr aren't writing updates for the miner then it is probably vaporware unless the company can show their code.
If it's not on this list you're asking for trouble:
https://bitcointalk.org/index.php?topic=456691.0