I use Lowes coupons all the time at HD, but never thought of trying a HF one.
I used to buy HD gift cards off of ebay, Was pretty common to get them for 12-13% below face value when I started buying them. Toss on a 10% off coupn and it sure helped at the checkout. But over time that 12-13% went to 10% then 8% and now a days 8% is tough to find.
While I never got burned, just doesn't seem worth the risk and hassle for much less than 8% savings. But I am planning a bathroom remodel soon and it might be worth stocking up on a few gift cards before the project to help ease the pain at the checkout.