I would say they are worth the money, Shoup MFG has the cheapest prices Ive seen. I noticed a difference in fuel usage in a days run after adding the programmers. I use a bullydog from SHoup for the 9600 and it works well.
We had our 9650sts chipped with a chip from saskatoon diesel, in saskatoon, saskatchwan,canada. www.dieselservices.com all he he wanted was the serial and model # of the pump and he made us one that was selectable with a toggle switch 15% or 30% (no, you couldn't switch one the go when loosing power,have to shut the motor down,would be nice though). i'd say it was worth the effort.
With the Schlagel chips I've sold there's always been an increase in fuel economy. As far as warranty, they unplug in seconds and are not traceable on the ecu. The local dealer has been good with turning a blind eye. A lot of Deere dealers actually sell chips right over the parts counter.