I have one on mine and use it all the time when on trips. When loaded heavily and towing I use the LOD function to give me visibility as to when to downshift.
The OBDII port on the '11 Sprinter is under the fuse box cover so with the gauge plugged in you cannot close the cover unless you either a) trim a hole in the cover, or b) unscrew the Sprinter OBDII connector, hook up the Scangauge connector and tuck the two of them away behind the panel it was screwed to (which is what I did). You can route the wire under the trim, rubber etc along the door/ A pillar to get to the top of the dash.