Thanks for mentioning GitLab this_user. I would be happy to answer any questions about GitLab.
More generally, I am curious how many of the "larger organizations" to which you refer in this context (clients interested in git-annex) are in the games industry, and how seriously interested your company is in trying to cater to that industry's needs? (Lots of game engines enjoy built-in first class support for Perforce due to how established it is in that vertical.)