I don't know about UnRAID but Samba at this point can do SMB Multi-Channel if the Guest / Client support it. As far as I'm aware though Samba only supports Multi-Channel via the multi-subnet method (multiple ports, each on their own distinct network segment). As long as the "big consumers" are on all of these networks, you should see CPU utilization improvements. Likewise, as long as your NICs support RSS (and at 10Gb most if not all should), then as long as incoming connections are coming from different IPs, they should also get divided up on multiple CPU cores.
Still, in general agree that for file delivery with large consumers (vs. numerous small consumers) clock speed is generally king.