They mentioned they're using libsass, a C/C++ port of the compiler. Although it's only an issue if you're using the source and not the compiled CSS. The same issue exists with v3 needing a LESS compiler.
The last time I looked at the PHP one, it compiled fine, but wasn't handling variables scopes in the same way of the JS one. This was a big deal for me.
Yeah, which is one of the reasons why I'm not a fan of Assetic in Symfony. The PHP versions of front-end build components are always lacking, unfortunately. But that's not a big deal in my opinion, you basically always need Node for a front-end application at this point for other needed tooling (Browserify/WebPack, Babel, etc.) so better to use the best-of-breed tooling and ignore Assetic as much as possible.
Yes, I tried using the React filter and failed. I switched to Gassetic (https://github.com/romanschejbal/gassetic) which is interesting but quite new and not well maintained. I couldn't make Reactify working with it which lead to way too long Browerify compilation time.
Next project I'll just use directly Gulp-or-whatever-is-fancy-then and find the simplest way to integrates it in Symfony/Twig.
