My experience with BlackArrow Lancelot has been disgusting from beginning:
1. I paid the order without escrow with 2% more to sell btc at Gox rate, as it didn't sell at that price, the seller didn't make refund to me as stated by them. They took my BTC without asking anything.

2. Cardreaderfactory shipped me my 10 boards with EMS without asking me first (I said them I want DHL or UPS). As consequence I have lots of problems with Customs and it was really expensive to me.

3. When I plug all boards, one of them never power on. I contacted their support and I didn't have any solution.

4. After three months of continuous mining I had to repair the fans because high noise and blocking.
I have now two boards with temperature problem too, that causes the mining stop, I will have to repair them too.

I recommend all of you to take all risks of losing your money with this company. At least make use of Escrow Bitcoin. I had order number 1771.