Personally I'd stay away from it - in boom furling is safer, and considerably more efficient - you can have battens etc and maintain a decent sail shape. Certainly I'd not have it in a boat destined for the high lats.
About 10 years ago I assisted another cruiser who had in mast furling. Approaching Fiji
he was hit by a squall that knocked him down, boom in the water
. The weight of the water
in/on the sail bent the furling mechanism inside the mast - could not move it in or out.
For the next 4 days the main was jammed where it was. Once arrived at Vuda Point Marina, I helped him remove the furler
and straighten the system out after removing it from the mast.
Every system can fail. At least with in boom furling you can always drop the sail - slab reef - if required.
I can certainly see the benefit of mainsail
roller reefing on a cruiser though.