Aloha Maunakea, I use the Schlumpf on two of my Dahons... the most recent is in a Jetstream XP conversion using the new Shimano 'Redband' 8spd hub with a Schlumpf 'SpeedDrive' (1.65/1 overdrive) crankset.. this gives me a completely planetary geartrain, straight chainline, large gear range (over 500%), is smooth, easy shifting and QUIET in operation.... you can think of the 'SpeedDrive' as replacing a 53/32 front chainring setup.. it is a robust unit, simple and repairable if needed, although I haven't heard of any reports of failure and they are said to be very long-lived..

With a small wheeled bike, you likely would not want to go with the'Mountain Drive (2.5/1 Underdrive) as the ratios would be quite low and more suitable for towing heavy loads.. the ' HighSpeed Drive (2.5/1 Overdrive) could be an option depending on what gearing you had in the rear and what overall gear range you were after.. as to worth for the money, in my book it is easily worth the dough if you want extended gear range for a small wheeled folder and where frequent folding could impact cable routings and alignment issues if a multi-ring front der were adapted .. in the US, the 'SpeedDrive' can go around $400 new.. Here's my Dahon Jetstream XP

Bruce