On the topic of overclocking...
Terrahash, for those that will be hosting with you, are you offering the option to overclock the miners?
When I visited Terrahash, they made it clear that the boards could only handle 350MH/Chip (not the chips).
Unless you transplant the chip onto another board there won't be much more room for "overclocking'.
Although Terrahash has had time to change up their board now, I wonder if the above is still true.