What kind of startup are you? Where do you want to use office? Who creates most of the content?

I have worked at a company that started with Googledocs and ended with Markdown (paper / design docs) and reveal.js for presentations. And that is something I can take recommend. Why? Because it is simple text that can be stored in a repository and you gain the ability to compare versions. It is easy to change and you can convert it to almost anything. The most important target is obviously pdf to communicate with customers. Nobody wants odt, docx or other strange formats that require more than a browser.

Convincing the technical people was not necessary or done quick. Non coder like the CEO did like the suggestion least, but it was a revolution from the base and people who code where mostly creating content or talking at conferences.