John, your posting is very interesting.

Your reasoning behind your choice of sheet makes quite some sense. However, different boats have different sailplans and very varying space for the sheets, so I don’t think there is such a thing as a generally ’best’ sheeting. The sheeting angle you get when close-hauled, is about the one I get in my Ingeborg when broad-reaching. At that angle, the sheet forces are quite light on my sheet too (3-part purchase, 35sqm sail).
As I round up for close-hauled sailing, the last bit of sheeting gets heavy. I can still manage by hand, but tend to rather make a couple of turns with the (1-speed) winch. Still, no show-stopper. Only if the sheeting space gets very narrow, as on foresails on schooners, would I completely rule out using central sheets.

As you say, the sail is prone to get creases (diagonal I guess) when close-hauled with central sheeting. I too got that, until I set up the Hong Kong parrels just taut enough to remove those creases  -  while still avoiding new creases in the opposite direction when squaring out the sail. 

http://goo.gl/r0fwCf

I generally divide my sails up in seven panels, which result in smaller panels. This lets me fit HK parrels without them intruding too far aft in the sail. I guess that your 5-panel sail would not like HK parrels that well, so your port-stb. sheets make sense. Actually, in the 80-es and 90-es, many British junks had the single sheet attached to a rail-to-rail sheet track. You get some of the same benefits that way.

Frankly, I guess we end up sticking with the sheets we have become used to, whether it is ‘the best’ or not.

If I were to try a two-tail sheet for a (large) Johanna-style sail, I would let one tail control the upper section and the other the lower one. This gives great twist control. I stress that keeping the twist right (= almost none) is an important performance factor. With telltales attached to the leech of each panel, you can see if the twist is right.

Cheers,
Arne

When I first rig up my sail with sheeting from the stern, I need a lot of effort to winch in the sheet especially approaching the close haul position.  The sail was creased by the stress pulling aft. I begin to question myself if its correct, because I remember seeing old master on traditional junks handling the sheet with single hand like flying a kite! Why is his sheet so light and mine so heavy? The master doesn't even need a tackle system on the sheet. He simply tie a quick release knot on the beam. The difference is that he is sheeting in from the beam and not from the stern, I discovered. So I try putting a trafer block to sheet in from the beam. (see diagram) It worked so well that I don't need any tackle system normally. In windy days, I put on a 1:2 system. There is no more crease on the sail because there is almost no stress aft. Moreover, I can now adjust the CE of the sail fore and aft easily because there is very little force pulling aft. Using two sheets is easy to stable the sail while gybing. BTW, the sheet is independent of the sheetlets.