I had the shop install the D-Fly unit when they setup my new bike in Feb. No regrets at all. I use it quite often to change the cassette setting when switching wheel sets since it is much more handy than dragging my laptop out the garage and setting it up. Not really necessary but nice to have. The only thing I have read is you probably want to use a PC to do the firmware updates since it seems to be much more robust than the wireless unit.