Amazing thanks!

So as far as formatting goes, it seems like it's only list formatting and small caps you've identified, am I missing anything else? (I am baffled by Docs' refusal to add small caps.)

But then as far as workflow is concerned, I'm not sure Docs is as unusable as you say it is -- the commit atomicity and comprehensive history aren't supported by Word either, are they? That's just a function of maintaining 20 separate copies of the file with each set of changes. You can still do that with Docs if you want to, rather than relying on the version history. And then "Tools > Compare documents" lets you merge in all the changes from another document, in an atomic way if you want. And if you want to use the revision history in a "master" version, you can used named versions as well.

Yes, everybody at the firm needs to use Docs. That's not unique to law -- every company that switches from MS365 to Google makes that kind of overnight transition, but it makes sense because you're paying one company or the other, not both.

It's the communication between firms that is going to be stuck in .docx basically forever though, so this is where Google needs to improve its conversion. Ideally Google would also build a "send a copy/transfer" feature so a firm can receive a Google Doc but know that from the moment it "opens" it, a new copy is made on their local Drive so the sending firm never sees edits or activity. But because that feels like it would be too easy to mess up, I think actual .docx file attachments will themselves be immortal, even if both sides used Docs.