i have a rt2870 chipset as well (edimax ew-7711USn). it's working with ralink's driver quite well (except for packet injection). with the apokalipse driver it does work, but worse (sometimes it doesn't switch to monitor mode properly/i have to run airmon-ng several times) and packet injection doesnt work either. additionally, airmon-ng reports the usb device as Ralink 2560 PCI with rt2500 as its driver.. quite strange behaviour imo and even more strange that it does work.. somehow..
any idea why it doesnt switch to monitor mode properly and why injection doesnt work? btw: Linux helge 2.6.28-14-generic (Ubuntu)