I’ve own mechanical tuners and pressure tuners and, at least in my samples, the pressure tuner is better and shows less noticeable off-band areas. A pressure tuner is as easy to use as turning a knob.
Below is my old Solarscope SF70 filter (a excellent filter BTW) that sported a mechanical tuner on a Borg 77 and my current LUNT 100 with a pressure tuner.
I really want one of those babies. Are they safe on the eye in terms of radiation etc?