Thanks for the pointer. I haven't seen that spec on cylinders before. 1500 mm/s translates to a top rated speed of 60"/second, or perhaps 1/15th of a second to stroke 3"... I doubt that I'm exceeding that speed at 150 PSI, anyway, although I've never timed the extension. Perhaps free air, without an implement. In any event, I've been using mine since around 2002, and have customers using them since maybe '05 without issue. Like my sex machines I'm using quality industrial components.
Yes, I'm sure the seals drag on the wall to some slight degree. That drag will disappear in the force to overcome the springs on extension.