Having had some trouble with the new “unified” firmware, I’ve just switched back to Dan’s python OSPi kernel, which is working just fine on the latest version of Raspbian (updated via rpi-update).
uname -a reports: Linux raspberrypi 3.18.10+ #775 PREEMPT Thu Apr 2 18:10:12 BST 2015 armv6l GNU/Linux
So, I think you should be good. Just in case, use something like WinSCP to make a backup to a desktop computer. If it doesn’t work, it is a simple matter to restore it.