Hi Robert,
You can go baremetal with xpenology, so basicly you can use any hardware as long as the drivers are present. you can search the forum for the lists of supported hardware.
i'm using a HP DL360 G7 (2cpu, 8cores, 16 threads and 44Gb ram) with a LSI SAS 9207-8i (SKU : LSI00302 | EAN : 0830343006892 ) and i'v bonded all 4 network interfaces into one.
and this setup works perfect.
as for the filesystem, any particular reason that you want to use ZFS? (BTW there is BTRFS support)