Tin, this is an interesting controller board and the stepper controllers run cooler than the basic Polou which in my experience was an issue with missed steps, hence I bought a Gecko.
This shop also has J heads and a better heater component for them than a simple resistor. This board supports 3 print heads and is cheaper over your way. I think I would go with the remote bowden extruder to get weight down if you go with multiple heads. I am still keen on ball screws. Feedback from a friend today keeping the Z axis travel level with dual steppers was a never ending problem as they would not stay in sync. He thought it would be better to run one stepper on the Z axis like he does with CNC mills.
I will think some more but wondered if the x and y were on a gantry running on a lead rail of some kind, driven by a ball screw and the Z ballscrew poked up in the air.
And I found a third NEMA 17 in my shed today.... so I probably only need steppers for the extruders.