Finally got the time to finish my new Z axis.
The taller axis (195mm vs 110mm) gives me more clearance which is great when I have long cutter or drills bits.
The XL belt seems to work well. I'm running 1:1 ratio with the 10mm pitch ballscrew and the 270oz stepper seems to keep up. The ballscrew, even if it is chinese, have less backlash than the T8 leadscrew I had. Even if it was preloaded. The only mising thing is the cable management for the spindle power and control.
I'm glad with th enew Z axis of the machine, I can now access ALL bolts easily so a bolt check shouldn't take more than ten minutes!