Hey Moshermax! I haven't ever played through a Port City, but I own the Matrix NL212 cab and I'll be honest in saying that it's working extremely well for me. When I switched over the AFX, partially to downsize my rig and save weight, I figured I should also try and save weight in my cabs as well. While I have a traditional guitar cab (Carvin Legacy cab) and a custom Xitone (1x12 FRFR), they each had their downfalls for my needs. Once I got my hands on a NL212, I was blown away at how light it was for the size. That's due to the neodymium speakers it uses over traditional, along with the lightweight tone woods. I don't use any cab sims with this cab, so I'm losing out on maximizing the use of my AFX, but I'm very happy with the tones I'm getting and can say that it sounds huge in the room.
Sorry I can't give you a comparison with the Port City, but if you have any specific questions regarding the NL212, I'll be happy to help out if I can, from someone who owns and plays through it daily.