Having used git svn on occasion, I can positively state that git's interfaces to other VCS's are slow, clunky and generally questionable.
The ideal case would be complete interoperability, where you could use git locally, yet collaborate on a daily basis with people using the project's non-git VCS, and no one would be inconvenienced -- or even necessarily aware of other developers' choice of VCS!
> The ideal case would be complete interoperability, where you could use git locally, yet collaborate on a daily basis with people using the project's non-git VCS
My impression is that this is the goal of the git "svn remote" work which has been slowly worked on for a quite a while, mostly by Google-Summer-of-Code participants.
With svn-remote support, subversion repos would be handled as a special types of remote at push/pull time, instead of requiring the user to use special commands and a different workflow. This same discipline would work for other repo types as well, and I think much of the infrastructure work being done now will be useful for implementing remote handlers for them.
The ideal case would be complete interoperability, where you could use git locally, yet collaborate on a daily basis with people using the project's non-git VCS, and no one would be inconvenienced -- or even necessarily aware of other developers' choice of VCS!