Yeah, I mentioned the CPU limit here: http://www.vicious1.com/forum/topic/z-lock/ (wow, hard to believe it’s been a whole year already since I got my kit)
I went with a 4 start 2mm pitch lead screw though for my Z so it’s only 200 steps per mm at 1/32 stepping.
I looked at Smoothieware/board too, it seemed like it would be a lot easier to switch to, but apparently even with the increased CPU power the actual firmware for Smoothieware is the same constant acceleration as Marlin/Repetier so I wouldn’t see much benefit. TinyG G2Core’s acceleration is apparently much different – but comes at the cost of being harder to switch to – it uses JSON (Chilipeppr) instead of normal gcode senders like Repetier Server or Octoprint and doesn’t have any presupported ‘all in one’ board available that supports 3D printing AND CNC cutting like RAMPS. Seeing it’s acceleration management though is amazing, here are some videos of it in action:
https://www.youtube.com/watch?v=tEXy6E8G154 (see how the ball swings left and right but then barely swings when the carriage stops moving)
https://www.youtube.com/watch?v=Om0wTqFA-Dw (it runs at 50,000mm/min and isn’t losing steps – granted it can’t print at those speeds obviously)
https://vine.co/v/hvYIdvQeZpK (swinging a big hammer around, and coming right up to but not touching a pair of buttons on both sides)