Mariss of Gecko has switched all of his test equipment to the amt-102/103????? capacitive encoders that you can get from Digi-key and highly recomends them. They also offer adjustable resolution via dip switches on the encoders.
Thats a single ended encoder and one of my customers had to add differential line drivers to drive a 10' cable reliably, but they worked ok after that.
You can't a beat US digital differential encoder though.
Manufacturer of CNC routers and Viper Servo Drives
www.LarkenCNC.com and www.Viperservo.com