New to the forum but old to Trek hybrids. I had the 7.2 for a few years (had a 7200 for a couple of years before that) and just decided to upgrade last week when I saw a 2020 FX 4 available locally (I didn't think the FX3 was much of an upgrade and didn't want to spend that much for the 2021 FX 4 Carbon). I have a couple of rides under my belt and just love it so far though it is an adjustment. It's a good bit faster than the 7.2 but less comfortable especially on rough roads due to the tire size.
I was planning on selling the 7.2 but as we have a little room in the garage (and I still love it) I'm just going to leave the panniers on it and leave the trailer hooked up for grocery runs.