If you score more mech Woodvil's and are looking for 22mm attys, I highly recommend a manta (if you can get one). It's 22mm, but the chamber is about 15mm. I'm running a single standard 26g coil at an ohm in a manta. The airflow closed off to about twice the chalice wide open. The flavor rocks. Derringers won't be that great IMO unless built to .5 or below (as with anything ymmv, some people love derringers at an ohm but they're typically using twisted wire)
The only reason I am considering 22mm atty's at all is because getting more Nuppin's is not likely to happen. Way back when I was on the second list, then third list for authentic black Derringer's from CH, but finally gave up on the ins and outs of praxis delays... and was only on the list for them in the first place because of the hype (that is speculative and an individual thing). I know nothing about the Manta, but will look into them, thanks for the idea. BTW, some of my KISS Nuppin' and Chalice builds are twisted builds.