QMAST favours endless loop winch systems because they control mainsheet tension easily, and are not liable to failure caused by having loose rope lying around.
Gaelforce II used a SmartWinch for the main sail, and a hobby winch servo for the jib. Separate loops allow separate motion of jib and main sails, which may increase controllability in tacking/gybing, or promote better speed upon exit of tacking.
The 4m uses a retail DC motor with a custom winch drum and retail Harken blocks to create an endless loop system. THe line is 3/16?" Amsteel. Brummel splices are used in place of knots to maintain strength. For full travel, the 4m winch must rotate 9(?) revolutions. An secondary output gearbox is installed on the motor to measure absolute position through the rotations of the winch.