We did it when we moved into a new house. Wanted to get rid of the inside tank, noisy burner, and oil smell.
Installed an underground tank, moved the heater location to the attic. Installed a high efficiency heater and went from a 125k btu oil to an 80k btu gas. (house about 2800 sf) Kept the same ac compressor, but changed the evap. Ended up converting one fireplace, cooktop to gas, and added the outside grill to the mix.
Was not big thing, would do it again in a heartbeat.