I have a Schaefer boom furler
and have not any such problem. It reefs
nicely. I'm assuming you're planning full length battens? These provide support to the foot (I usually reef so that a batten is just above the boom to minimize chafe on the batten stitching - this has the effect of tightening the foot).
I suspect that the builder's experience was also due to an incorrectly cut sail. Schaefer provides very detailed sailmaker
instructions that need to be followed. I would look around for a sailmaker with extensive experience with furling booms - hopefully Schaefer. I would ask him to call Schaefer and ask questions. My understanding is that Schaefer is easier than Leisurefurl for the sailmaker because the excellent mast
track and feeder is much easier on luff tapes.
With any furling boom you need to keep exactly the right boom angle or the sail will try to walk when being furled. Schaefer uses a rigid boom vang
that is part of the gooseneck support. You don't adjust this underway. The builder's description of cranking down on the boom is certainly not my procedure.
The fixed boom vang
also means that the sail maker has to be especially careful with the leech construction to avoid a hooked or open leech. For this reason, my leech has extra reinforcement to minimize stretch. Insist that the sailmaker get things right such that your leech is good at each reef spot. Mine is.
has much better shape than I ever had in my last boat with a mast
furling system (and that had vertical battens). I also have a huge powerful roach. The Schaefer furler has never given me a moment's problem.