Note this path with giftcertificates.com works with non-travel providers too. So that's definitely a way to double dip (triple dip if you also count the CC used to pay GC.com). Two concerns are:
1) You lose credit card protections (e.g., return protection, warranty extension) on the item purchased
2) If you return an expensive item, you could be stuck with a very large gift cert/store credit