Having used both over the years, we have no problem with the idea of loose-footed mains. They make for easier outhaul adjustment because there is less friction in stretching the foot. Some make much of the "shelf" and its "endplate" effect on the efficiency of a sail with a boltrope foot. We have found that when the outhaul is stretched for beating the gap tends to close up on the boom anyhow.
Off the wind you get a more uniform shape right down to the bottom of the sail.
If your sailing involves removing the mainsail between outings, a loose-footed sail is easier to bend on and unbend at the end of the day.