I've been using M1 for 1.5 months. Here's my experience as a coding SaaS founder
Speed. Aww yeah, it is lightning fast! My daily setup: Postgres, VScode (+48 plugins), Sublime Text, Slack, Discord, Spotify, Thunderbird, Telegram, Chrome, Firefox, iTerm, Figma, Alfred. All simultaneously. Not a single freeze so far. Each app opens instantly.
Apps. As you know, there is a chip incompatibility issue. And there is something called Rosetta to fix it. So I expected some problems with apps. But in reality, I did not have to care about this. There's no difference between M1 and Intel to me.
What went wrong. My biggest fear was not being able to launch my development environment. When I typed brew install python@3.7 in the terminal I got this error: "The x86_64 architecture is required for this software.". It instantly made me pale because this means I will have to carry 2 laptops to be able to code my product The problem was solved quickly by upgrading the project to a newer version of Python. Thank goodness our dependencies did not mess up because of the update. The next problem was nodejs v11 which was needed to launch the product locally. yarn start took ~2 hours (HOURS!) to launch. Each update took ~5 minutes to compile. The development process was awful. I got pale again The problem was solved by moving to a newer nodejs version. Again, the dependencies did not break up. But the things could easily mess up because nodejs dependencies are complicated as hell. Now it compiles instantly, yarn build takes 30 sec.
Keyboard. It is much better than the previous generations have. Apple has fixed it. It is not as brilliant as the old one from my MacBook Pro 2012, but still fine.
Why Air, not Pro. AFAIK, the Pro version has these differences: better battery, better mic + sound, more ports (+2). I did not find these features significant enough to pay extra. And I also dislike Touch Bar.