I modified the Vaporesso VM-22 tank so it is the only one I can speak to directly.
With regard to loop size, I have some input. I don't know that MF actually made a conscious change in loop size. I have an older Walnut LB from a local shop. The loop is big and the cell hole is way big. Someone really reefed on this one in the factory. It is my DD. My copper slug is 14.5mm for this LB.
I have two others - one ancient converted to MD and one very recent factory direct. Both of these are identical and won't fit the 14.5mm slug into their holes without scraping wood. The modification I did for
@Choices were also made to 14.4mm diameter. Therefore yes, there are some outliers, but for the most part, 14.4mm is the right diameter.