The only difficulty is afaik, you can only apply one coupon per order or something, i.e., you can't buy 10 miners and apply 10 coupons to that order. You have to apply them each individually; i'm not sure what i will do about that.
I'm quite sure you can apply coupons in bulk. In fact I bought 20 miners in one order, all with coupons. If you mean one coupon per MINER - that is correct.