The X5 (and the X3 which I have) has that stupidly hard spiky sole tread (TPU?) that wears down about 5mm per ride if you ever put your feet down on gravel/tarmac/terracotta tiled cafe.
The X4 uses Velcro for the main strap, and it's 2021.
But pretty much any road shoe can be converted to SPD with a Shimano SM-SH41 SPD Cleat Stabilising Adaptor. Not to be confused with previous SM-SH40 which fell apart by all accounts. Here they are on another pair of Fiziks:
The X5 (and the X3 which I have) has that stupidly hard spiky sole tread (TPU?) that wears down about 5mm per ride if you ever put your feet down on gravel/tarmac/terracotta tiled cafe.
The X4 uses Velcro for the main strap, and it's 2021.
Buying Shimano next time.