As no one has replied to this I will offer an opinion. I have use both methods and each has it’s pros and cons I think. The single run with rubber is probably easier to set up – I have used that on racing and scale boats. The problem is that the elastic needs replacing quite regularly and there is always a slight load on the sail winch. Also, it will probably be above deck so is a bit unsightly on a scale model.
The continuous loop idea is good if you have good access into the hull or can arrange for the whole caboodle to be on a removeable board which attaches inside the hull and can be removed through a hatch. Have the winch mounted one end and the continuous line passing round a pulley at the other end. The sheet can be taken of attachment points along the loop.
Using it on a single sail makes life easier in that you don’t have to arrange for varying sheet lengths. There are a number of good books available outlining various methods- a lot will depend on the type of boat being built.
Hope this helps a bit,
Ian