Building scss/js with hugo hasn't been an issue for me yet - the theme I use shipped with its own build pipeline, as I imagine others do. Fortunately, the theme dev organized it well.

I didn't know about the cache busting with jekyll. Right now, I just toss assets into the 'static' dir so I don't think Hugo does anything with them, but I think there are other ways/shortcodes to serve them. Overall, I'm not super happy with hugo, I just latched onto the "it's fast" marketing line because I've had bad experiences with Ruby's performance. As far as my main gripe, the go templating engine seems pretty bad.. Either that, or I don't know how to use it well. I believe templating engines are swappable, however.

Overall, my content is so simple (photos + text) that the usability issues don't bug me yet.