What software are you planning on running? The N100 is a pretty stout chip for my router. Not all file systems need insane amounts of ram like ZFS
That said you may want a full sized pcie slot depending on what hard drives you’re running. At work our raid controllers are gimped by their PCIe interface. Even with regular ass hard drives they will out pace pcie 2.0@x1 speeds since most cheap HBAs are PCIe 2 or maybe 3.