Welcome to Audiocircle. As you've probably read, you can go very far if you're willing to take the DIY route (electronics or speakers). Also, it's very fulfilling to know that you've created what you're enjoying.
Anyway, Danny's designs are all very solid and some of the best values you can find in audio. In terms of the A/V-3's vs. the N-3's, I haven't heard the A-V series, but the Neo based series (monitors, N-3's, etc) are very, very nice and have been receiving good reviews across the board. So, IMO, I'd go with the N-3's. Another direction to think of is the O-3's, which I own. I use them in a room about the same size as yours, and they are terrific. Very relaxed presentation and fills up the room with ease. I think they like the taller ceilings, and should sound great as long as you're able to get them at least 3 feet from the walls. But, you really couldn't go wrong with any of the choices.
As for the Infinities, my 2 thoughts would be either set them up in another room to have a 2nd system or donate them to a friend who is interested in getting some speakers. I have a pair of speakers I'm not using on "loan" to a friend who's enjoying them, so everyone's happy.
