I have a PL2 that I got off of everyone's favorite auction site. It's actually re-certified by a technician so it has been tested and is accurate.
I had an autocross event yesterday - for those unfamiliar, it's a bunch of cars out in a parking lot driving as fast as possible around cones.
I was trying to get speeds with the PL2, and it was NOT easy! I obviously aimed for plates and headlights, but you have to keep the gun damn steady and you have to keep it on the same point as well. The way the cars are moving in an autocross generally involves swerving and zig-zagging, making it very difficult to hold a beam on a single spot for long enough to get a lock. These cars were ~300-500 feet, so it wasn't even very far.
Lesson to learn: if you want to be impossible to get a speed on, do the Nascar/F1-style tire warming routine of swerving left to right. Hopefully then the LEO doesn't ticket you for reckless driving or something.
I imagine that it's easier in a straight line, but even then the hand tremors are definitely an issue.
In summary - it's a LOT harder than you think to get a speed, which means that even the little bit of disruption that a jammer does is helping immensely.