I have just done this with the HUB444 conversion kit, which I got from mtb-direct, and a Superstar 9mm QR axle.
Easy to fit – the only sticky bit is the old QR axle is threaded at the end and if it is stiff it is not so easy to undo.
Best solution was with a couple of molegrips (not molgrips…) which grip tight enough to not slip.
The HUB444 kit just has two axle ends which just push into the hub and have a couple of rubber O-rings to hold them in. Then just insert the 9MM axle.
Thought I would mention it as it was so easy to do.
Dunno if it is any stiffer, but I had lost some confidence in my normal Hope QR as it had come undone a few times – so it was either buy a better QR or the kit and SS axle.
Haven’t gone for the DT Swiss RWS solution yet as I have seen some people complaining that it is fragile.
