I run SR9 and SR5 on the 532A board. During an upgrade from 29.x to RC7 or above or from RCx to RC10 after reboot the wlan1 and wlan2 interfaces do not appear. Rebooting does not make them return The only way to get the interfaces back is to disable them is telneting and using int wireless set wlan1 diabled=yes reboot then re-enable each using winbox or command line. I have about 40 wds clients per interface. Nstrem is running on SR5 no Nstrem on Sr9.
I also find the cpu takes a while to settle down after the reboot too.