@Juku
Do not subvert what I said. It makes me think bad of you.
So I basically said you should make your mod to a mod, not the opposite, as you claim. Since it will keep working even after updates (although not 100%), also there is a chance Solar might look into it to pull some content; modyfying master file is idiocy since nobody sane will try going through your changes, nothing is worth such time and work investment. Unless Solar wants to relinquish the position of the main developer to you, but I don't think so.
I did not mean to misrepresent you, and apologize If it came across that way.
That having been said, I still fail to understand how your quote actually supports the position of making a 'mod to a mod' being superior in case the 'submod' is large enough.
Any update by Solarius will have to be manually merged anyway, due to how different the balancing is by now. Updating, say, 0.4.2 into what's currently available in the 'Idea Proving Grounds', you'd get an unholy mess even if my changes came in a 'submod' format. It won't be 'not 100%', getting 75% would be an achievement. You of all people should understand this.
And maintaining only 'minimal change' rulesets makes MY life hell for modding purposes, while not making Solarius' life much easier, and is of no benefit to anyone else except some hypothetical replacement of his, who I have no desire to become.
I see no better option than what I've proposed and implemented right now: Solarius and other interested parties can ask for specific changes they like, and can identify what they like by either ruleset diving (bad idea in general, which has essentially been your whole point as far as I can tell, but feasible for small things and Solarius has done some of it), reading the Ufopedia and playing quick battles (easiest, but most shallow), and trying a quick run of my version (sabotages playtesting for XCF, but If people have already gone through it once and want a somewhat different experience, why not?). When asked, I can provide a 'current' and/or 'backported' implementation of the changes.
If you have an actual idea how to improve the above, by all means, please elaborate.