Using Mercurial instead of git is also a bit like using another kernel instead of Linux. It seems unnecessary to use something else when you already have something that works, but it's useful to have working options in case you find yourself using a device without a Linux port but with FreeBSD support, for example.
True. Having two options instead of one is always good.
Today I read some (most?) documents on the project's site, and I see that it's very similar, but on the flip side it looks like interactive rebases are not as easy as they are with git, and I really use them a lot (I write several features and test them all together, so I often squash my fixes in the original commit before pushing).
Also, I don't like much the data model (which is why, I think, changing the whole history is not as easy as with git).
Thank you none the less, it was interesting reading.
/alessandro