> Plastic SCM [...] developed an importer that supports the fast-import
> format introduced by Git and widely used to migrate from other systems
Most source control systems assume a one-time import because they are so awesome there's no doubt you'll want to keep your code there forever, but the trend is to support at least Git semi-synchronously.
Kiln Harmony is a little bit different than that. We are aiming that you can push a Git repo to Kiln, clone out an Hg repo, push that back to Kiln in an empty repo, and get back exactly the same Git repo you started with. This means that both format types are completely equal--and, more importantly, they're both canonical.
Plastic and Perforce are solving a very important, but fundamentally different, problem: how can I use Git to interface with my proprietary SCM? These problems tend to evolve solutions like git-svn or hgsubversion, where either you're keeping the initial repository around as a base (I believe Plastic does this), or you simply don't even care about it at all (e.g., in Perforce, its repos are assembled from arbitrary slices of the main source tree, so the same commit may have different files entirely from the one your neighbor is using, even though both repos include the same chunks of history).
Those are also valuable tools, and we did consider making what would amount to a Git front-end for Mercurial. But we really wanted both systems to be peers, both canonical, and that mandated a totally different set of design decisions and restrictions.
It's not that what Plastic and Perforce have aren't cool. They're just fundamentally different.
Plastic and Perforce are solving a very important, but fundamentally different, problem: how can I use Git to interface with my proprietary SCM? These problems tend to evolve solutions like git-svn or hgsubversion, where either you're keeping the initial repository around as a base (I believe Plastic does this), or you simply don't even care about it at all (e.g., in Perforce, its repos are assembled from arbitrary slices of the main source tree, so the same commit may have different files entirely from the one your neighbor is using, even though both repos include the same chunks of history).
Those are also valuable tools, and we did consider making what would amount to a Git front-end for Mercurial. But we really wanted both systems to be peers, both canonical, and that mandated a totally different set of design decisions and restrictions.
It's not that what Plastic and Perforce have aren't cool. They're just fundamentally different.