Well I have heard good from UCCNC but mach4 what I have heard is still work in progress. but if guys out there got working combinations with mach3 and steppers I should get my system reliable with mach3 too. otherwise UCCNC or Mach4 doesn't make difference.
Update from testing:
Today tried Z axis stepper removed from leadscrew so It was plain stepper spinning. I marked it and give it same program again and suprise, still losing steps.. If feedrate is same both ways it wont "lose" steps of course it loses, but same amount for bot directions so the endpoint is same as starting.. but that's how it works or.... not.
seems that those TB6600 leds are lighting up as stepper makes "bigger" noise. like resonance or something.