Unfortunately, Kiln was never an option for us. We are a git shop, and while I do have a lot of respect for hg, we just do not want to use it. But VCS integration in FogBugz was never the main problem.
We currently use FogBugz with GitHub (private repos) and it works very well. I wrote a bridge that connects both APIs together, so we get fairly good integration. Information about commits and branches gets attached to FogBugz cases and we get a smooth workflow out of it.
The problem with FogBugz is that it is slow and has a number of minor annoyances, which grow to be a pain in the long term. Such as Fog Creek refusing to make the software automatically mark "#1527" as a linkable case. You have to write "case #1527". Quite annoying, especially if you don't run your FogBugz installation in English!
There are other things, such as obsolete Windows-based character encodings they insist on using in E-mails sent from FogBugz. Also, hosted FogBugz is slow. We spend a lot of time waiting.
Oh, and the default "VCS integration" features in FogBugz are from the CVS/RCS era and they still haven't been modified, even though they sell Kiln. The "Checkins" field in every case is file-based, so there is no way you can attach modern DVCS changesets to it.
I reported all of the above problems more than a year ago, and nothing has changed.
All in all, while we do use FogBugz (and pay quite a bit of money every month for the pleasure), we are looking for alternatives.