I can see the attraction of the AXBB-E for 4 axis systems with modest I/O, plus the inclusion of analogue outputs to control the VFD speed. It even has a jumper to allow either 5V or 10V range for the speed. I think for the majority of hobby users it would be a perfect little unit.

But I need 5 stepper motor control, so the extra space for the additional board just to driver the 5th axis makes it similar to the UC300ETH+UCBB in terms of footprint. More thinking . . . .