If I understand correctly, you want to eventually run two 4CH NVR's on your home network and each NVR already has 4 PoE ports in the back. The nice thing about this is that it will only take up two ports on your switch when you connect your NVR to the network. There shouldn't be a problem with this so long as you resolve the potential IP conflict when installing the second NVR, considering that most NVR's of the same brand and model have the same default IP address.
As far as blending both systems into one view through PSS software, I would rather go with two separate HD televisions. Maybe a 19" or so.
Regards,
Jason Rosalez