I have used a vernie throttle a few times and had no issue with them. Found the trick is use the screw function for most power changes unless you're looking for a large RPM/Manifold change (such as T/O, Climb to cruise etc...). When a large change was needed I would do the majority by pushing the button and then the final tune up adjusted back on the screw. Same with landing, did most of the adjusting right from final on down with the screw function.
No probs at all, and not really dangerous.