I did radiant floor heating for my shop/hangar. Top quality installation. Not sure I'd do it again. Here are some thoughts.
The PEX install is nice and pretty easy. However, you will have multiple runs from the distribution manifold and each run needs to be close to the same length, otherwise long runs will be colder than short runs and flow rates will vary. The installer said runs were about 200' each and not more than 10% variance. While it may be a DIY, it may not be cost effective once you include all the materials, manifolds, connections, and a few specialized tools.
Most hangars are not insulated well enough - I have the sandwiched insulation between the exterior metal skin and the skeleton of the building. This is no enough. Also, its hard to avoid air leaks in a hangar and tall ceilings don't help either. Thus the system, even in my relatively mild climate of coastal Virginia works pretty hard most nights in the winter (and then sits idle during the day). I'd say it runs from about 9-10pm until about 8-9am.
If I am using my shop daily (eg if it were currently a business) then heating it full time would make sense but what I find I am wanting with my current project schedule is to "hold" a lower temp during the week and then bring it up to 55 or 60 on the weekends. Radiant does not do this well.
My hangar is big - 75% of a 60'x80' with 18' at the eaves and 27' at the ridge. If I had an insulated drop ceiling at 10', it would make a big difference but that is not an option for a number of reasons. I'd also need to add another layer of insulation at the walls but again not an option without a significant effort.
If you do the extra insulation work up front (and allocate the budget for it) it will make a notable difference.
By contrast, the house is also radiant and well insulated and the system works wonderfully. I'd say the biggest differences being the better insulation and the 9' ceilings in the house vs very open space in the hangar (which makes for a very large air mass).