I think that both CatDancer and rntz have good points, the problem is that they are working on different things and thus have different perspectives.
CatDancer is mostly working on libraries - independent pieces of code that, while they may redifine some things, or make minor changes to the base language, mostly leave it alone. These can be written easily in the "shortest distance from arc" method and still work well together because they don't actually change the base of arc. This also means that while VC is useful in development, it is hardly needed in publishing.
rntz has been working on porting changes from arc2 to arc3 and some other hacks, many of which require major changes to the arc code base itself such as his coerce hack. These need to be VC'd so that they can be understood by other users of Anarki, and so that they can work more easily with eachother. Since many of them create major changes to the codebase, it can sometimes be a challenge to get them to work together and as he says plain diffs would be a nightmare.
I may be summarizing a bit much, and I'm sure there are more subtleties to it than that, but it's how I understand the situation.
As far as I can tell, they can be handled separately. The publishing of libraries and miscellaneous code can be done without publicly visible version control, but the Anarki base should probably be versioned.
Git is still a good choice for what we're doing, as far as I can tell, because for one thing all it is is scripts built for managing it's base. That is the essence of the so-called porcelain. I'm sure it won't hurt anyone to add a little bit more in the way of domain-specific tools. They might be useful to others as well.
So it sounds like we have to things going on here:
1) We need a meta-data and library publishing system for people to share code that they've written to use with arc.
2) We need a slightly better method of handling changes to the arc base so that people can coordinate massive changes thereto. I think that individual commits works ok for minor changes, but it rapidly gets complicated to handle if they start stepping on eachother. That's when we should switch to "branches" which can be interpreted to mean alternate conceptions of arc. Case in point being the hygienic version of arc in the hygiene branch.
At some point we just admit that the lisp community is hopelessly built on making their own incompatible versions of lisp, and everyone makes their own fork of arc. Magic merges and rebasing can only handle so much incompatibility in the history of the system.
I wouldn't dismiss the possibility of using darcs for your project. git was designed to merge tens of thousands of lines of code in a fraction of a second; that doesn't mean it isn't useful for other tasks, but it also doesn't mean that darcs might not be better for the kinds of tasks that you find yourselves needing to do.
Git was also designed to have a fast, simple back end, with a script based front end. Each command that you're used to using with git is just a shell or perl script that calls a few basic git functions to mess with blobs. Therefore, it is easy to add new tools and scripts. A good example given the darcs context would be: http://raphael.slinckx.net/blog/2007-11-03/git-commit-darcs-...
My point is that the architecture of git allows us to write scripts that work at the same level as the other git scripts; we can keep or leave the others as desired.
