Metz just added HSS support on the Metz Mecablitz M400 for Fujifilm X series cameras with firmware 1.1. Here is the message a FR-reader got directly from Metz:
“As of now a new firmware version (1.1) is available for the flash unit mecablitz M400 for Fujifilm. This new firmware version enables now the HSS-flash-mode of the Fujifilm cameras X-T1, X-T2 and X-Pro2.”
Check out more and download the firmare at the Metz Mecablitz product page here.