Yes that is true. I did the radiant floor heat in my garage here in NY and it gas been great for 13 years. Very efficient, like you mention. It is 600 sq ft.
This new shop will be 2400 sq ft and will need a stand-alone heat/cooling unit. Too far from house to plumb hot water. So, i was figuring the split unit to do both. Otherwise, i’d need a boiler/heater for the heating water, and a separate ac unit. I can still consider radiant if there is an economical way to do both.