I have one of those inclinometers set up for my stoker on the tandem (my son); he gets a kick out of feeding me updates from it. Cheap and requires no batteries! I cut the cord about 3 years ago and have been happily riding electronics-free since then. I found I started enjoying riding more that way. I like to pretend I am retired at least and ride without a plan sometimes. I think what you are doing is spot on, keep the auto GPS handy for a backup only, just in case you do need to find a route home from an unfamiliar place.

Don't get stuck with an electronic wife telling you to turn left and right and that you are not riding as fast as you did last week or that some guy from across town is faster than you are.