<Tips the hat to Bob Wahr, as I don his used, but obviously effective fire retardant suit>
I've never attempted it but from what I understand branching and merging in subversion is painful, well merging a branch is at least. If you have time peruse these google results.
Your Google search keywords show your bias there. From my searching, this was certainly the case in SVN versions prior to 1.5.X (which added merge history), but most of those articles in your Google search are either 2 or more years old, or referring to versions prior to SVN 1.5.X.
For the record branching and merging in HG is painless since every copy is essentially a branch. Just thought I'd throw that in there.
I did read this from the link you posted earlier to the Mercurial Docs. It mentioned that EVERYTHING in Mercurial is essentially a 'fork'. It also goes on to say, that Mercurial is VERY good at merging, so this shouldn't be a problem.
I then took a leaf out of
your book and punched into Google 'Mercurial merge sucks' and hit some interesting articles. Some comments I found, were saying that as recently as early 2007, Mercurial's 'merge', which it relies upon, was 100% wrong...go figure. I will keep searching for more opinions.
There's probably a very good reason why SourceForge and a little company called Google uses SVN, but I will find that out for myself.
Bring it.