Ok thanks Gerry. If I go UB1 route I'll bear that in mind.

For the AXBB-E - reading around a bit and my concerns about how to drive 5 axes appear to be justified. The manual suggests the additional axes (anything more than 4) can use the spare I/O channels. But these are isolated outputs which can't drive step/dir ( I believe).

This means I would need to add a ribbon cable connector to the front of the unit, and adding an expansion board such as UCSB or UCBB to a second board to get access to the other non-isolated outputs for the 5th axis. I think this means I am no better off than using the UC300ETH + UCBB in terms of space and general layout.

Does anyone have a different experience of getting more than 4 axes out of the AXBB as otherwise it looks like a great little unit ?

There is the naughty approach of pairing up step/dir to the 2 Zaxis drivers, but of course I would never do that . . .