Eden, I was just going to say what you stated. Duh, the faster group got to the top because they were the faster group. Nothing to do with GPS.
I am not a fast rider either, but I am a good climber. I readily admit I hate gadgets and technology in general, but I do have bike computer, which is used mostly to see how far I've gone. Some rides are focused on speed, some I don't even look at my average. I quit wearing my HRM years ago, because I was just looking at it too much. Plus, it got interference with everything. My HR is higher than a lot of people's when I ride, yet I am not experiencing any difficulty. I know I am fit. PRE is enough for me.
Of course, I don't ride with traditional type groups, so hence, I feel no need to use any of this stuff. When I feel the need to compete with myself, I stick with the faster guys in my group, and the fact that I can hang on with them is good. Heck, we're all old guys, anyway, so I tend to compare myself to the couch potato who thinks they are washed up at my age.
Then I feel a lot better!