Good deal IMO. Only concern for me is whether a click thru from big crumbs and/or using a 10% discount could invalidate getting the miles. Some discussion on pointsguy's blog that either of those would invalidate. Entering a discount code would seem to be more risky as it's clearly intentional on the part of the buyer (they put the code in), but referrals are not necessarily intentional (could have clicked thru hours before the purchase and come back) and the delta offer shows up regardless of what site you clicked thru.