Kind of annoying to have to click on each unit in turn, then click on its upgrade button, to know whether there are any upgrades needed.

In that sense, this is a step backwards from original FE (which didn't show the button at all, unless upgrades were needed).

I don't recommend repeating what was done in FE: if the button isn't there, then I don't know whether it is merely in the overflow list, until I check the overflow list for that unit. That's at least as annoying.

Just gray the button out, to indicate no upgrades are available?