One of the requirements I had was that I can use the single cable USB-C 'docking' stations we have at the office, like my colleagues do who are on the new macbooks.

The great thing of the X1 is (imo) that is has USB-C with TB3 and charging capability like the Mac, but it also has 2 USB type A inputs.

That said, charging over USB-C is not ideal, the supplied 100W Lenovo power brick (unfortunately with proprietary connector) will charge the laptop much faster. It wouldn't even surprise me if the laptop actually loses charge under high load when connected to a USB-C charger. My current MBP also does that with a 60W charger connected.