I am in the process of knowing Mercurial versioning system better, and I am considering convert from SVN.
Anyone already converted? Was that difficult for you and your team
I don't have experience with mercurial (use git instead) but the difference in experience between a good DVCS like mercurial or git vs. svn is something that you truly can't go back from once you've gotten past the learning curve.
I had a job recently that involved going back to using a centralized svn repository after using git for a year or two. I approached it by using the git-svn bridge, and found that I had great control over the commits compared to svn, and could make the commits and branches sit, roll over, and play dead in ways that gave me a useful advantage over my svn using co-workers, in addition to the large volume of commits that I made by comparison because of the very granular and frequent nature of doing local commits. It was a great benefit.
I really really recommend giving yourself some time with a DVCS.