I still like the CSMIO IP-M with Mach3.

The real benefit of the controller support for axis slaving/homing (e.g IP-S) is homing on index. Homing on index has almost 100% accuracy/repeatability of homing/squaring as it doesn't rely on the sensors accuracy but you need motors with encoders, e.g servo drives with index pulse..

Otherwise I find the software homing/squaring quite reliable and do not see any real benefit for a homing sequence performed by the controller.

It is even possible to home on index with Mach3 with a simple macro. Not sure about gantry squaring on index but it may be doable as well.