If you go with the hot water, in floor system, consider making zones. Inevitably, you will have a primary work area where you spend most of your time. Make that zone one and add other zones as needed, each one with a little pump that you can control with switches. If you want the whole shop warm, turn them all on the night before you plan to do your work.

I recently did a lot of electrical work in a large custom home. It has hot water radiant heat. I would set the t-stats at 60 degrees from eight to ten. Sixty felt really warm. Shut them off sometime after ten as the sun heated the house through the windows and it was comfortable all day.

 

I've spent some time in a floor heated shop and it's definately a different feeling of warmth (comfortable but just different). Heat radiating up from a concrete floor is very nice and efficient if you keep it heated but if it's shut off it will take longer to get a room up to temperature than ceiling mounted or forced air heaters.

 

In floor heat is most efficient when you just leave it on. Set it at 60-65, and forget it all winter.

 

Very true! I have radiant heating in my first floor and takes a loooong time to get to temperature. If the space will be constantly occupied then its the way to go, if not, there are much better alternatives.