I have one, and flipping it from "laptop mode" to "tablet mode" adds noticeable friction, especially if you have e.g. a dock connected. Then again, so does having to carry around a tablet.

For an office job I'd take the external tablet, since my laptop would likely be plugged in all the time.

You could also keep it permanently in tablet mode and use an external monitor, mouse, and keyboard. Just don't underestimate the mode change.