I have both the Soyo SY-6BA+III and the Asus CUBX. Generally, both have been stable, but my overall feeling is that the Soyo is more stable.
Also, I have not had the need to try Soyo customer support. On the other hand, on both CUBX, the mouse does not appear in device manager at all (a microsoft mouse or a logitech mouse, both with drivers suppied by the w98se disk and by the disks that came with the mouse). The mice work fine. Device manager can not identify the what device irq12 is being used by (the mouse). Asus tech support is just ignoring me.
As I said the soyo is my guess for the more stable but I do not know about their customer support. I do know about Asus customer support, though.
Paul