My experience, also using T and X series laptops matches yours. Some issues with resuming from sleep a long time ago and with firmware on a docking station once

My experience, also using T and X series laptops matches yours. Some issues with resuming from sleep a long time ago and with firmware on a docking station once but otherwise only one gripe: I've never been entirely happy with the fan control. I found in the end with my T440s that leaving it to the OS worked well enough. Previously, with older X series machines, I had to both try to optimize and also ended up replacing fans.