Yes, it's a classic case of premature optimization.

* As you mentioned, you get most of the benefits from gzip compression. * You pay a major debugging penalty for having your code minified, since it's much harder to figure out what happened with minified code. * After the first request your code is going to be cached locally, anyway, so we're only talking about the initial request. * Using a CDN for your libraries will buy you much more. It's not 100% relevant, but if you're worried about download speed, this is one thing that does make sense.