I haven't seen the XFX in action, but my Sapphire (non OC version, but it has the same cooling solution) runs dead silent when idle. I set the fan speed to 20% with automatic increase. Temps max out on 65 C during stress testing and when I do that I can hear the fans, but not very loud. During gaming I never hear them. Mine overclocks like a champ by the way, but I'm sure the XFX does as well.
Hope that helps, I think I'd just get the cheaper one honestly.