Originally Posted by SloopJonB
I've used one a fair bit on a Hunter 38 and I don't like it. We've had problems with a curl in the sail up high jamming it - had to hoist the skipper up with tools to unjam it and have had to be VERY careful when furling ever since. There is very little room in the slot for any wrinkles etc. to fit through. I also find it very hard work to wind in & out - lots of friction. It has to be winched the whole way. It takes much more effort than conventional hoisting from the boom.
I vastly prefer lazyjacks.
I've had a very different experience using in-mast furling on several different boats - primarily a Catalina 36 and a Saga 409 but also a Hunter 306 and a Jeanneau 45. I've had very little trouble with jamming - you need to keep the boom angle within reason and keep slight tension on the outhaul when furling, but the in-mast furling systems I've used have all worked pretty smoothly. I find it to be much less effort than hoisting a traditional main. So much so that I think people use the mainsail more. It's common to see boats with traditional mains sailing jib-only because of the effort involved in taking off the sail cover and sail ties, and hoisting, then flaking, tying, and covering to put it all back away when finished. With in-mast you just roll it out, sail, and roll it back in.