James,
If I had a conversion project ahead of me and the preferred mast position favoured a high-balance sail, I would choose Slieve McGalliard’s Split Junk Rig (SJR). Since I like to use camber in my sails, I would be worried if the mast had to sit near the max camber point, as with the Van Loan planforms (.. however, Paul J Thompson, with his La Chica could maybe prove me wrong there). With Slieve’s SJR this problem has been solved.
If you have looked at my rigs, you will see that I have stuck to 70° yards and little balance in my sails. Originally, this was because I wanted low-balance sails, since they give minimum distortion of the camber (..and the SJR had not been invented yet...). Today the reasons have mainly been that on the projects I have had, the best mast positions (far forward) have dictated the use of such sails.
Even though I have not sailed with a SJR, I have read Slieve’s reports on it (plus reports in Practical Boat Owner), and I see no reason why it should not be good. It even is a junkrig, basically, with the sheet controlling several battens. Therefore, it will handle and reef just as easily as any other junk, without needing to tie down the battens.
In comparison, Beneteau’s experimental wing sail and Paul McKay’s AeroJunk only have their booms sheeted (right?), so will most probably need some reefing lines at the leech end for each batten. In addition, although Paul’s Aerojunk sounds and looks to have very good aerodynamic, I guess I am more confident at the sewing machine than as a mechanic, so my choice would be Slieve’s SJR: The SJR calls for some sewing challenges, but the battens are just straight tubes.
Anyway, good luck!
Arne