Doing the math on the compensation offer...
Assume you bought 2 S3s from Batch 1 .75 BTC x 2 = 1.5 BTC
A refund of 7.7% = .1155 BTC
A coupon for 10% off of your next purchase of 2 miners at the current purchase price of .725 BTC each = (.725 * 2)(.1)= .145 BTC
Net difference is .145 - .1155 = .0295 BTC, or about $18.29.
That's only getting a $9 per miner bonus on a future order, not knowing at this point how future batches will hash.
Perhaps the 10% off coupon will apply to an unlimited number of miners on your future order, in which case the coupon will be of greater value. Or maybe it won't have an expiration and you could use it when it becomes of maximum value. But to me, it seems like money in hand is the better option.
Money in hand is the smarter option, but I'm such a sucker for coupons. It was such a brilliant move on Bitmains part, though.