3com 3c996b-t support?

Is 3c996b-t gigabit ethernet NIC supported with the tigon3 driver? The driver in the kernel lacks documentation as too what it supports, at least I couldn't find any.

On another note, 3com provides GPL drivers for this card, is there a reason why these cannot be merged into the kernel? Or is it basically what the tigon3 is? Has anyone tried these drivers out and found out which performs better? Should I stick with what 3com provides or go with what is in the kernel if it works?

Thanks,
Steve