Hello! :)
I got a TS4 and loving it.
I have 2 x 27GP950. If I plug them both directly to the Macbook Pro via HDMI (both with a USB-C to HDMI adapter), I can get them both working at 4K@120hz.
Altough, if I plug those 2 adapters directly into the dock, then only one of the monitors is able to do 120HZ. The other one stays at 4K@60hz.
Is this a bandwith limitation?