Hi Mick,
I did. I was going to report back when I had something more definitive.
The file from the Google track or history or whatever they call it looked quite strange. It was very full of the sort of stuff that gives you a creepy feeling about Google Maps. (Mind you, I'm pretty tolerant of that stuff. I actually post - often snarky - reviews when they send emails about my experience at wherever they last surveilled me.) Photo Mechanic couldn't make heads nor tails of their file, no matter what format I transcoded it to.
I grabbed a phone app called GeoTracker. It's meant for hikers. It outputs your track in any of several formats. I took it on a short walk around the neighborhood and Photo Mechanic appeared to read it OK. It generated an accurate track on the map in the Import GPS dialog. And Photo Mechanic correctly reported the first and last waypoints and times, neither of which happened with the Google file. But I didn't shoot any pictures to match with the track. While I'm hopeful, I haven't completed the loop. I'll go out again and shoot some pictures.
More when I know more.
-Carl