I have installed SUSE SLES 8 and 9 on X335s and X336s.
They are both as stable as anything, just using the stock kernel (note, if using IBM's TSM (and specifically connecting to a tape library via fibre) or Oracle you MUST stick to stock kernel at the moment as they lag WAY behind with updates to their software for new kernels)
With Qlogic you will need to get the latest drivers from qlogic.com and for SLES 8 you MUST download the broadcom network driver from the broadcom website (unfortunately it is only available as a tarball source so you have to compile it on the machine.
I have a short piece on installing SLES 8 and 9 on x335 and x336 with SATA at the following address:
Any other questions, just give me a shout