I've done this for years. It takes me about five minutes to run the numbers, set up the transfer, set up the auto monthly payments, and make a note on my outlook to remind me to pay off the balance due before the deal's expiration date. I also just dump it into my ING account, I know I can get higher interest somewhere else but too lazy to do the paperwork. I generally don't bother if I don't at least have a gain of $1000 pre tax. Been doing these promo interest rates for years, no negative effect on my credit at all.