ORIGINAL: olnico

Yes, the Firgelli actuators have 0,1 mm of slack. Pretty much unbeatable.
The problem is to ensure that 1 lb-torque at approx. 15 mm/s is enough on a 20 mm travel.

I think that the only way to find out is to order a PQ12 and a L12-30 and try both solutions in-situ.

The problem with the hydraulic solution is the amount of elongation the system will take before the piston actually starts moving. This is mostly due to the elastic nature of the plastic tubing used. When the hydraulic fluid transmits the pressure from the command piston, the lines expand a bit and that creates some sort of hysteresis in the piston motion. Very difficult to control, especially considering the fact that the tubing elastic point is varying with the outside temperature...