Hey Scott @jscottsmith, hey Derek,
Regarding the Buildbotics.com-derived Onefinity Controller, I agree to what Derek said, and I always remember to consider the good price with which you get a 4-axis CNC controller that can run the g-code program you like. It allows proximity sensors as limit switches, it’s the Onefinity machine that lacks those, not the controller that lacks the capability. You can retrofit them to get perfect positioning repeatibility (what is not provided with stall homing). The new version of original Buildbotics.com controller even allows to run closed-loop steppers because it has an additional connector with the step, direction, and enable signals laid to the outside so you can attach external motor drivers. What it lacks are the optocouplers, the pins of the AVR are directly on I/O port, so you got to take care yourself how to attach external things.
What I like on the Masso is this:
Image: Masso: Replacing Optocouplers
The optocouplers are not soldered, but all socketed for easy replacement. This is something that you have to build yourself on the Onefinity / Buildbotics controller.
What I like on the Onefinity / Buildbotics Controller is joystick control, and I would recommmend throwing away the flimsy gamepad and instead using this (available here).