ZFS raid write performance?

[Quartz]

>> Writes over NFS 3 are synchronous. Writes over CIFS/Samba are likely
>> not.
>
>> write performance with multiple
>> clients.
>
>> Finally, single GigE is _slow_.
>
>
> I realize I've left out some possibly critical information.
>
> This box is a dump space that needs to receive files from widely mixed
> "clients" (*nix/Win/Mac/desktop/laptop/etc) across a LAN, so the file
> share software is Samba and the client machines will be connecting with
> (at most) a single GigE.

... and, these files will not need to be read or copied back off the 
server for a few days.