Almost all the videos of installing the gear change sensor I have seen show it being put down near the derailleur and I have read comments about cleaning being necessary. I live at the end of a mile of dirt road which is either very dusty or very muddy.
Recently I saw a 3yr old video by an Australian woman and she put it right next to the shifter. To me this seems to be a very good outcome for a little bit of extra fiddling around. What do others think, especially Johnny if he reads this?