Soon as I got my X the other week, I put RubiX Focused 2.0.1 on it. My friend had been running it and he found it was the most stable, solid and fastest Rom for the X. It's a bit stripped down, but that's ok, it's more like an OG Droid Rom that way, and I'm used to that. I've had zero problems with it and zero reboots.
its been a stable ROM since the beginnings of this ROM but up until now it constantly reboots on me when i connect my phone to my computer via usb mass storage. I think this is because im still on 2.0 and not on the update but i dont think the update will fix that since it just streamlines the startup scripts or something like that.