A couple of things I learned during this promo:
1) The limit of 10 per card is hard coded into the system
2) It's very sneaky of S&S but the system will allow you to purchase many multiples of 10 and print coupons for them, it's only an issue on the redemption side.
3) The system has a hard time processing a $0 transaction and requires an override (at least at self checkout) always go at least a few cents over.
4) Although the the coupon is a generic code it will not work with a Stop and Shop card that did not purchase any GC's during the promo period. (I'm not sure if it's because it was never used, of that the transactions need to match the coupon one for one. The difference would be if the other card purchased on GC deal can it now be used for many?)
5) Even the nice managers get annoyed when they need to override six coupons back to back.