Superb modeling and photography!!
I don't like the vinyl material that Montex uses, I think it's about the same as Oramask 810 which I used for awhile until it the adhesive reacted with the paint, and also because it tends to shrink over time. I'm using sheets made by Tamiya now and it is a great masking material. Never leaves residue and may be even thinner than the Tamiya tape we get in rolls.
I haven't used the paints you used here but they sure look good.