I would love to see an upgrade option for the 10440 with a adjustable rhodium pin instead of the fixed brass it came with and a tail cap replacement that locks like the new P+ 14500. It would not be hard to make the top/bottom parts and sell them as upgrades.
With my 10440 I needed to make a spacer for both flat and button top batteries as the tube is 3-5 mm to long. Protected button tops fit the best, but they were still off by a few MM and required an o-ring. Unfortunately, protected batteries worked awful in the unit so I switched to unprotected years ago and have never had an issue. Find the right atomizer and the mod is a dream.
The only real problem is that it does not lock on the switch making this perfect size pocket unit not so pocket friendly. This is the main reason I don't take it out too often.
I would also love to pick up a P+ 18650 if they ever make it back in stock. I wish Super T would start selling tubes for the 18xxx mods so that people can swap them out to use different battery combinations. Atmomixani got it right with the Nemesis mod; give people the option to do several battery configurations with one mod. We pay enough for these things; why not give people options!?
I hate the tube gap/tube lock ring on the ELA mod [makes the mod look ugly IMO] which is why offering several tube sizes is a better option. The single tube S/P+ mods are sleek and sexy, I don't see how selling tubs for a reasonable price or including them in a $180 mod is such a hard thing. Not only would this help stock issues but it would simplify the growing number of mods on the Super T website. Why do people have to buy a completely new mod just to go from 18650 to 18350?
Again your only real competitor right now [taking into account build quality & production availability] got it right in this regard, I hope Super T considers the same business model.