For your room, the dual VTF-2 MK4 setup will definitely have enough max output. If you are uncomfortable spending more, then don't.
But the PB12-NSD and the VTF-3 MK4 are a step up from the VTF-2 MK4, and those two are equivalent in class. If you go and and ask in the AVS subwoofer forum
which is better between the PB12 and the VTF3.4, you'll probably start a war between HSU owners and SVS owners over which is the best, and get claims from both sides (like the one above) about one being undeniably better than the other
I'd go for the PB12 over the VTF3.4 in your size room if choosing between those two (BTW: I don't own either brand) because they would best fit my personal preferences. But you have a lot of researching, learning, and thinking to do before you could make an educated decision of your own between those two.