I recall this causing compatibility issues and that Buster11 was the best chip (but not error free)...
Buster 11, DENEB and DMA will lead to lockups in hardware if ZorRAM is being used heavily.
This is a "feature" of Buster 11, a remnant of the famous Buster 9 lockup which was claimed to be removed while stepping to rev11. It is still there, harder to trigger, but it will hit you just as a matter of time and statistics.
But: I have written a new firmware for DENEB which can cope with that situation. The DENEB FPGA takes over some buster work, and allows (according to all our tests in lab and at customers) stable operation of DENEB DMA and Zorro III RAM.
Firmware is available on request for testing, and will be published as free upgrade for all DENEB customers as time permits (i.e. I need to find some time to recompile the FPGA sources in a cleaned up version :-) )
Michael