It looks like the VTF3 mk5 will have an advantage in either mode, and the kind of advantage can change based on what mode you run the VTF3 in, ie if you want more 25 to 30 Hz output, run it in two ports mode, or if you want deeper extension, run it in one port mode. It doesn't look like the VTF3 mk5 will give up anything to the XV15se in either mode. Basically it is a higher performer.