Simon, I have been here thinking what could I possibly say regarding this issue...
As you may know I am not a fan of those things, for many particular reasons, that is not the point, we all sail in different conditions and for different reasons.
However, if was dedicated to crusing, I would possibly think about it, I would probably do as Cam did, and get a furler boom, intead of an inmast, many reasons why.
The biggest ones being the fact that on a boom furler you can still have battens and thus better sail shape, and the reefing is still done vertically, still alowing sail shape control, along the sail's center if lift, which is approx the first 1/3 of the sail, which if needed could be used to get somee better sail control and speed, never know what one could find in a passage.
I also have never seen (there aren't many with that here) or heard about jaming of in mast furlers, but to me, the concept of it, for blue water, might be risky, not because the system is good or bad, but the more moving parts, to me the worse, more stuff that can fail...was this clear? But generally the idea I have is that it is OK for coastal relaxed cruising, and like everything in life you get what you pay for, there are good systems out there, as well as a lot of crap. This to say it really depends on the manufacturer.
I, still prefer the lazy bag and lazy Jack system (when cruising, which is what I am doing now), I still can do everything from the cockpit, and I do not sacrifice performance, altough I think its uggly as hell, that and the dodger...practical, but ugly.
As far as all the stories and people sailing mast furlers, passing boats with regular sails, that does not mean the system is good, it means the people sailing the regular sails are morons....(G)