I just did the opposite and love it. I was burnt out, now I have time to play with some new ideas and technology. Meetings where you can sit there, be sociable and think of other stuff. I can take a few days off, turn the phone off and know the place isn't going to burn down without me. Luxury. In a few years I might move back but I feel like I've done my time.

Cool! What do you find is the best advantage and what is the biggest downside working in a small startup as opposed to a big corporate?

Biggest downside: a lack of established process. Big corporate had too much process at times, but there was normally decent enough tooling around everything. And there were teams to do everything, which really allowed you to focus.

Advantage: More control over what tools I use. Always something interesting happening, and knowing that the growth of the company is directly influenced by your work.

I am also terrified that being able to impact the company/culture means that I will lead us down the wrong path.

That's an interesting worry to have! Sounds like fun, you definitely won't be bored at work.