I use the VPAF Hot in the bridge and the VPAF N in my Gibson SG...
The VPAF Hot is an overwound PAF style pickup...It has more mid content,is very note articulate,crisp but not harsh highs and strong tight lows...Cuts very nice with my gear and my band....The pickup has pretty strong output also..
The VPAF N is like the Hot,but wound to have less output and less mids,but it's pretty strong and "woofy" in the lows unless you adjust it down a bit from the strings...This pickup is also tight,punchy,nice chimey clear highs,note articulate...
The 3D character is due to their "air" technology,in that they use an A5 magnet,but there's "air space" between the magnet...This phenomena is something you do hear when you use these pickups...
Not sure about the Air Classic,but I was going to switch out this pickup for the VPAF in the neck for less lows and less mids,but I got the VPAF N working good by lowering it and shortening the pole screws under the pickup..
Dimarzio guys claimed the Air Classic was on the lines in tone and character of the Jazz N from Duncan,but I didn't try it? I also have a Jazz N here if I need to swap the VPAF N out? Both of my Dimarzios are double creme and that's why they're still in my SG....They look really great in the guitar.