I've often had the same experience, people's workflows are pretty ingrained (in general, not just screenwriters). But I've done some pitches where a writer had a lightbulb moment, and realized that collab and versioning really would make things easier.

I put great emphasis on the app behaving similar to current screenwriting tools, and the collaboration/versioning features just being there when they are needed, so the change in somebody's workflow can happen gradually.

I'm curious which approach you had considered. And would love to get feedback from writers/filmmakers of all backgrounds: m@arcstudiopro.com

I work for a movie production company and have been thinking of creating something similar - especially the collaborative and versioning feature as in github for screenwriting. If you like I could ping you via E-Mail as well, since there are some features crucial for (at least our) workflow. Revision aka colored (replacement)pages, excerpts for set dressers etc. But so far it looks really great and I hope it'll be able to replace Final Draft at our company someday.

CelTx has most of those features already. Last time I checked them out they were working on collaborative features; I don't know if they've released those yet.

WriterDuet already has collaborative features--indeed, that was the original goal of the app. It also includes support for replacement pages and everything else you've suggested that you need.

Yes, please do ping me! m@arcstudiopro.com

I'm especially interested in learning about production company workflows. Our tech was designed with team workflows in mind and we plan to add such features soon. Would be great to get your feedback on what we have planned.