I’m a developer who’s pretty much always used Ubuntu, and haven't bothered digging too deep into other distros. What are the modern features I’m missing?
You either get stuff sooner or get stuff more stable, you can't have 'rock solid' stuff sooner.
Things like mock and fedpkg make modifying upstream/bundling your own stuff up super easy. Then add in COPR (like PPAs) and it's a feedback-loop friendly setup