Dear Domingos,
Thanks a lot for the answers.
1) Igus bushings
1.1) I didn't count on room compensation done by bearings, and from information I've found Igur bushings are obviously loosing material as they age. It depends of course of the combination of rod steel grade BVC has choosen / iglidur type. Including tolerances on every part.
1.2) They seem to be much more silent than bearings, at least from the tests I've seen (just sliding differents bearings on steel rod, with no clue of the bearings quality which is important to know for an objective test). But opening the door to a 4thDimension-Ghost-Ninja Mode where power supply fan is the loudest part... "sounds" great!
2) Nimble
2.1) According to
https://zesty.tech/products/the-nimble? ... 1732311297:
It will fit any Nema17 stepper, suggested torque rating is: 4kg/cm.
I must admit that I don't know what to do with this information, so it's yours now
For what I've found on their FAQ, Zesty states that "[...] you want a stepper that has low inertia (so it can start moving fast) and low inductance (so it can handle fast stepper pulses)." So in short I have to check if your stepper are in required specs or if another stepper will fulfill requirements.
2.2) The potential movement transfer delay may require to fine tune the firmware as you already did for the springiness of filament.
Assuming that 1. Steel cable has a very stable behavior over time and 2. Filament's springiness depends on its material: in theory (or in my head only, dunno

) it might provide even more accuracy as the square drive cable is one unique material leading to a potential constant compensation.
I understand that previous statement can be overthinked, as I don't know the compensation needed in both cases.
Well, first thing first, I have to place my order.
Best regards,
Gni