That's interesting to hear. I think it's worth a support ticket to investigate your setup. I've got around 20-30 clients, about 10 of which are 802.11ac (iPhones, iPads, iMacs, Samsung TV's, and a PC with a Broadcom chipset), and they've been consistently reliable on the 5GHz radio with a R700 and R600.
But of course, my setup working for me does nothing to help you with your setup. My past experience is that Ruckus support has been helpful in troubleshooting a specific issue, which is difficult to do in a discussion forum environment.