I really like the radiant personally, I've worked in a few different shops with radiant and forced air setups. The radiant heaters are more efficient and since they heat the objects in the heated space when you open an overhead door for awhile and then close it, it gets back up to temp much faster.
For example: A 32 ton M109A6 howitzer takes a full 4 day weekend to thaw out in a small forced air shop, roughly 35 x 40, from being in the cold out side. We would pull one in early Thursday morning and next Monday it still felt 5-10 degrees cooler in the shop than the rest of the building. After swapping to two radiant tube heaters from the 4 forced air heaters I could pull one in at 8 am and be totally thawed out, almost warm to the touch and back up to 65° inside by quiting time at 4 pm the same day.
I had a buddy order it from here in Draper:
Unique site dedicated to helping you find the best infrared tube heaters, garage heaters and patio heaters for your application
www.superiortubeheaters.com
It's their UA series 20' 40k BTU. I'm close to $2k with the wall thimble to horizontally vent it and a Nest thermostat e (almost free after rebates with rocky mountain and dominion)..