See here is my problem. I also have protected Trustfire 18350 Batterys and 2 of those bairly fit no spacer needed. However my AW IMR's need 4 spacers. This isn't a big deal to me because I can just get wider magnets (spacers) and only use 1 but if he makes it to much smaller protected batts might not work. Although if I recall correctly he also said the new ones will take 16340 I believe so 18350s is a moot point.
I've always been careful when designing to allow the biggest batteries that are commonly used to fit, even if just barely and then use spacers for the smaller ones, no other choice unless I sell multiple sized mods for different battery brands and that is just crazy talk
It does look like 16340 batteries are beginning to rule the day so I am looking closely at making that the battery of choice for RSMs as well.