Thread:Requests for comment/Minifier/Output comparison/reply

To debug you'd use source maps (bug 45514), or debug mode (not the one we have now, but a much more simple one, like debug=unmin, one that only bypasses minification and nothing else, file mapping is overrated).

As for the differences, none of those should be able to negatively impact performance (if anything, it might optimise performance) in a significant way. And debugging is imho not a relevant factor for the minified code as you shouldn't look at the minified code (in modern browsers we can use source maps, and in older browsers we can debug using non-minified mode).

The Yoda conditional and variable renaming are for better gzip compression as they result in more commonly repeated patterns.

There's a few other compressor transformations it can do you didn't list that I am worried about, from a code integrity point of view (some of them are not generic / unsafe, and might only work for sane code, not arbitrary code that might be on the edge of validity in the first place).