This is such an interesting thread. I have considered feeding round bales for years but I have held back because of concerns about waste and the danger of a bad bale.
To the o/p, I would be very careful about feeding anything free choice that is loaded with alfalfa, especially to ponies. You could be risking laminitis with that setup.
My horses are out all day/in at night and I would love the ease of letting them munch on a round bale rather than slogging through the snow to make piles of hay twice a day. Iām getting closer to trying a round bale after reading this thread.