javasource
6-4-3 = 2
Buy the newest model of the pocket radar. I sat next to a Stalker and a Jugs (guns, not people)... smiling... the readings were always within 1 mph. The Constant mode is a breeze.
I have both a Jugs gun and the Pocket Radar, and I have also found that the readings with the Pocket Radar are within 1 mph of the Jugs gun. It's an excellent product for the money. Much better than the Bushnell guns which read slow. The other nice thing is that it isn't as obvious as a Jugs or Stalker so you can sneak in readings if that's what you're trying to do. Or you can get pitchers at their best because they don't realize what you're doing and thus tighten up trying to throw faster like so many do.
As for out of the hand v at the plate, I don't think that really matters. It's just a number. If everyone else is comparing out of the hand you want to also, otherwise your pitchers will suffer by comparison. After all, it's not like if you hit a certain speed at the plate the ball suddenly acquires bat repellant.
Radar guns are for measuring progress and claiming bragging rights. If you're doing the latter, you want the highest reading you can get (without cheating). That will be out of the hand. If you're doing the former, either will work -- as long as you are consistent in how you measure it.