Yes, isn't that what the OP was asking about, rather than the Stay Certs? Since the Gift Certs are denominated in US$, they will be subject to the hotel's cash exchange rate, which is usually quite a bit off the cc exchange rate. I had a cash cert for $50 from Hyatt once (can't remember why they sent it to me), and used it at HR Kyoto for a loss of almost 10% off the central rate.