There are people that work on chirp that had to learn mercurial as their first SCM, having never known another thing. The reason I haven't proposed a switch is to avoid switching to thing-de-jour and constantly having to have people learn new things.
I fall into that category.
I'd like to hear from at least Jim, who I believe learned mercurial just to contribute to chirp, and who does enough work to earn a blocking veto (IMHO).
Things have been upside down for me since my wife got very sick late last summer and eventually lost her battle with cancer in October. I'm still trying to recover and have many additional responsibilities have been forced upon me leaving me with very little free time for myself. I'm not against learning something new. But it won't be a priority for me any time soon.
Jim