There may well be the start of an on-going problem here with manufactureres using the word "digital" in as sloppy a manner as possible to imply superiority where none exists because it is a new buzzword.
A fully digital system should be one where all of the signalling is in the form of coded numbers, and is handled at every stage between the control stick and the servo arm by devices which handle such numbers. Sadly, anything which uses chips from the "digital" part of the chip makers inventory tends to get called "digital". I suspect that digital in this case means that although the servo probably responds to a normal (i.e. on for a set length of time, off the rest of the time) signal, which is sort of binary, this control signal is then handled by a processor to control the motor.
I would be tempted to e-mail the manufacturer and ask. If you dont get an answer look elsewhere. Let the manufacturer know you have gone elsewhere, and why (it pays to be helpful).
I will stick with my standard servos which I have modified into winches. They work on the principle that when the stick is centred, nothing happens, when moved forward or back, the winch winds in the appropriate direction as long as I am shoving the stick. With a 12 or 15 mm double drum, there is plenty or torque for handling the sails on my 1M size yacht, and the speed is OK for my kind of non-competitive sailing.
