Bill,
I have radiant heat(hot water) that was installed when I built the shop. It has a crawl space underneath so it under the floor(as opposed to in a slab. I agree with you that taking everything out of your shop would be a nightmare. However, I do think that the radiant floor heat is one of the best decisions that I made when building it. You don't know it's there other than the shop is not cold. No moving air, filters, exhaust, etc. It keeps my shop extremely comfortable all winter.
I agree with Jeff, put the pipe under the road and cap it and keep your options open.

Jim