Of course, if it is mounted on a windows box before being shared out again, then you still have a single point of failure, don't you? I doubt performance would be better that way, anyway.

You're probably better going with NAS, since you have fewer failure points and also don't have to use a windows server. Within a year, NAS autofailover will be out. I'd go for the NAS, if possible. It's one of the most flexible options (dss has built-in rsync capability and data backup capability and even some level of AntiVirus protection that is only available for NAS volumes).