Many thanks for your feedback on HelpStudio.
We currently don't have plans to add the source control providers that you have mentioned. I have logged this as a feature request to be included in a future version.
It would be great if anyone else who has used Mercurial and would be keen in seeing support for it in HelpStudio could post a reply here - we're trying to figure out the level of interest for this particular source control provider.
Support for Mercurial would be great, since we have switched most of our projects from SubVersion to Mercurial.
We're looking to upgrade to Mercurial at some point, so support would be good.
In the mean time though, how well does HelpStudio work if we were to just use Mercurial on the files without having integration available?