The benefit for developers (some), the pain for users (some). The problem is that one is getting and another one is paying the price.
the "users" of slime are developers. i may be way too short-sighted on this but i can't imagine that more then a marginal fraction of slime "users" need to install darcs only because they want to get the latest slime.
but this is getting more about protecting different point of views then a fruitful discussion about how to make things work better. i proposed something i think is better for everyone, i made my share of the work, and i'll let it die unless others back up behind the idea. (which means that there's no need to argue _against_ darcs while i'm alone, because nothing will happen to the official slime repo)