I have recently deployed 3 seperate sites using the RB333 board. I have 2 HPOL 120 DEG 5Ghz sectors and 1 5Ghz panel that acts as a Backhaul from a Virtual AP at the main tower. I run Nstreme, best fit and 10Mhz spacing. When both sectors are running the backhaul is luck to get 1Mbps.... When I disable the sectors the BH gets 3-6Mbps. This confirms to me that RF leaks too much when the cards are stacked on each other. The cards ar R52H cards. ALSO, when I disable Nstreme on the sector cards, the performance for the BH goes up to about 2Mbps.

Has anyone else experienced this... is there a way around it besides breaking out to a seperate BH box?

antenna seperation and frequency seperation are what is required.
if these fail then you have to also adopt signal isolation (single radio per rb/enclosure).