The N3 design is fairly new and because of the length of time most people spend building out their speakers, not too many have been built out and 'reviewed' just yet. If you look up the AV3, you'll find a lot of information...this is a big update/upgrade on that design, it seems.
The N3 (I'm assuming), N2X, N1X and even OB speakers have a similar 'sound' that Danny is known for. Most of Danny's speakers you've heard were likely tailored a bit towards Mark's 'sound' or weren't taken to the highest level with various simple upgrades like No-Rez.
The tweeter (Neo 3) is fantastic and very airy with great off-axis response. The midrange and vocals from the N2X and OB7s I own are fantastic and a huge huge huge upgrade from the Refs...and I'm fairly certain the N3s go quite low (-3 is 40 hz, likely lower in-room).
These are a huge upgrade from the AV123 speakers you own, though I know little about Aperions.
Danny is also making a new design using Kevin Haskin's new driver (from DIYcable) that will be very impressive for a HT speaker. The monitor version (Tweeter/Mid) is expected to go down to 40 hz

The tower version will be pretty crazy. That design will be using the 'Encore' tweeter you're familiar with.
As someone who owns the N2X, I highly recommend going for the N3s and expect you to be blown away by their performance. For surrounds, you can use the cheap P.E. cabs if you want to make that part easier on yourself.