I just picked up a 12" M5 2016 Macbook during the last BF. I also have the WD15 that I am using with my Dell XPS 15 9550.
With fully up-to-date firmware, the dock works very well for my setup.
Connected to the WD15 dock are
- One Dell U2412M (1920x1200) through Display Port
- Logitech unifying receiver for keyboard and mouse
- Gigabit Ethernet Cable
- External USB drive (WD Passport 3TB)
- Headphone
As far as I know, everything works, the dock charges the Macbook (Approx 20W).
It also works in a clamshell mode.
Seems to be an ideal docking solution.
-- Update --
Dual monitor sort of working. The two display can only mirror each other. It does extend from the Macbook built-in LCD but the two external monitors can only display the same thing.