For what it's worth, I've uninstalled Garmin Express from my desktop PC and laptop after trying it for a few weeks. All it seemed to do was slow down my uploads to both Garmin Connect and Strava. I saw no reason to keep it. I don't know what it was supposed to do besides make uploading rides easier, but it didn't do that.
Quite possibly the worst thing Garmin have done, it will be coming off my computer too. What is the point of using "Express" when connect works about 100 times quicker? Connect takes a few seconds, Express takes about 5 minutes.
Well, now, here's the deal. AFTER switching to Modern Garmin Connect, I had no choice but to reinstall Garmin Express, and I've found it DOES upload my activity to the Modern Garmin Connect faster than lightning. With old Garmin Express, though, it doesn't do squat. So maybe when the change is made to Modern Garmin Connect permanently, this will all make sense.
I'm having to Uninstall Express every time I want to use my Tanita BC 1000 scale on my Windows 8.1 machine (something I didn't have to do on my Windows XP machine) :-(