My first introduction to furling mains was watching the crew of a Hinkley in the BVI battle a jammed main for three hours in a 25 knot breeze. I thought "wow, that's a real dumb thing to have on a sailboat". So I became one of those sailors that thought never! And this one experience coloured my whole view of in-mast furling for the next ten years.
In 2004 I bought a new boat and it came with a furling main. In five years of sailing in the Bahamas ( I live aboard this boat during the winter) I have yet to have a problem with it. I have grown to love it and use the main a lot more than when I cruised in my CS36M with a traditional main.
Yes, the leech is hollow etc., etc. but for my kind of sailing I usually have more main than I need as it's usually blowing. One of the advantages that I love is that when the sail is over and we're at anchor my buddies are flaking their sail and covering it while I sit in my cockpit sipping my rum.
No more dancing on the coach roof in bouncing seas putting the sail ties on when entering an anchorage.
Most jams are caused by operator error. Unless you're going to race a furling main would be my choice. Someone mentioned wind whistling in the slot, I don't have that. Just learn how to use it properly and it'll be fine.