Regarding AXBB-E. People over on cnczone haven't been able to add 5th or 6th axis straight onto the additional IO fitted to the board. They are mainly all designed for switching. The way to do it is via port#3 with an additional UCSB or other bob.

I have the UC300eth with a UCBB. This setup limits you to 16 out and 18 in through 2 ports. You need an extra IDC16 cable and a terminal block for use of analoge port. Or you can plug directly with dupont cabling/connectors.
I prefer to use seperate components because if 1 fails it's cheaper to replace.

UB1 uses 3 ports + the analoge as standard giving more IO over the UCBB.
For the other 2 ports (4+5) there is the UD1 daughterboard. My view is that if something fails it will be a large cost to replace it again.