Yeah i don't know all you're vape experience, but try not to use anything you learned from VG or VapCap here, they're just essay too different man. I think you can het it with practice if you stick with it, even try using nothing else, it really seems to be your technique. You can draw faster when it is hotter, but it's about pulling heat from a temp rising steel mass into the stem through your herbs, so a controlled draw in some sense, and really the 18mm can do small loads, just need to cover the screen so no air can get through without vaping herbs.
When I used the reducer, I was actually not filling a small 14mm bowl (getting a screen to stay in there would be a real bitch, and i remember Pak saying it liked to move when you stirred, and you had to stir bc of the narrower airpath making hot spots) since it left a half inch in the reducer, so the reducer was actually my 18mm bowl and then I would put the other end in a bong i had, it wouldn't really be what youre looking for, but
@Alan is exploring using cork or silicone to make a seal so you can use a narrower tube and his two screen system for micro no stir loads... However again stirring is possible to avoid here, again it comes to your technique, stay at it man you can get it.
Yeah posted above, ultimately no real benefit, you can search in the Zion thread for my exact report and photos though
PIU has some specific stipulations that he and RBT disagreed over I believe, among other things I am sure. However another US retailer has joined in, I think VaporGeekz was mentioned before, and they may have various accessories including male to males as well
Also the dark spot is easily avoidable, I rarely get it, just hone your technique further, other variables etc. In Zion it is even less of an issue with the production heaters, it roasts through the center with an even extraction from some form of vortex airflow, Milaana is more like my orignal beta Zion heater, a bit simpler (and slightly smaller than both). You can get a more even extraction laying off the button with using residual heat to finish hits, plus draw and pack