Honestly? Not really. I’ve been working with tools, fasteners, and other stuff like that in both systems for so long that it’s just kind of automatic. There might be a momentary hitch while I switch gears, but nothing notable. Though I suppose it helps that you have an objective thing there to deal with - it doesn’t matter if you call it 39-and-change thousanths of an inch, or 1mm, it’s the same distance on the object, so as long as your measurement is accurate, it’s the same cut.
Honestly, it’s more annoying if things are in different tool and fastener systems. A half-inch socket isn’t the same as a 12 or 13mm socket, because it’s 12.7mm across the relevant points. Threads aren’t always compatible, even if they initially seem that way. Not to mention different measurement standards - a half inch Whitworth(British Standard, measured by bold diameter) is different to a half inch A/F(American, stands for “Across Flats”), and they both have different conversions to metric, where they have them, along with different thread standards that also aren’t always compatible with the others.
But, that’s getting off point, getting back to it, the one that gets me is temperature. I have zero internal reference for how hot or cold anything in imperial degrees is. A 60 degree day? Fuck knows, could be hot, could be cold, could be pleasant or shithouse, it’s up in the air.