The slotted headstock, custom neck/fret width, color, and finish can all raise the price of an Emerald nylon string guitar. My first Emerald X10 nylon had a paddle headstock, standard carbon fiber weave, and was priced in line with other available cf nylon string guitars. The slotted headstock is mostly a matter of style. My Rainsong Parlor has the paddle head and it works just fine.

I don't know if Alistair would be inclined to make a basic X20-OSN. As Fazool notes, there may not be enough demand for a production model. However, there does seem to be a demand for Emerald custom nylon string guitars--I can testify to such demand as I'm on my 4th one