I know what you mean about taller DTs for the Boxx. My mouth kind of rests on the shelf around the DT when I use my normal size ones with a Boxx. Not sure why.
I like the extra air you get from the Boxx. I've noticed the 510 nut has a wider bore opening that the standard BB and the SXK Delro too.
I use 2.5 coils and the 3.5mm af insert in my Qbix, but you know I like a slightly more restricted draw than you. It's nice running the Orbit more open though - somewhere around 4mm af.
Good to know about the nut. I got the drip tips today, and what a difference a mm or so in height makes!
I was using 13.5mm ones, now I've got a 16mm in there and it's perfect. It's also the right width so that it doesn't overhang the 510 nut: