Don't know off the top of my head which switch Proto are using, but almost invariably the microswitches in high end markers have an activation weight of 25 or 80 grams. Even 80 grams is hardly a stiff trigger pull (and will help to combat bounce and reset the trigger quicker between pulls).
If your trigger is genuinely stiff, it sounds to me like something else must be going on other than the actual weight of your trigger pull.
Is the trigger rubbing against anything? Catching on any of the wires? Do the bearings need cleaning and oiling?