Conceptually in my mind it is the same thing. Yes, I recognize that psychologically the feeling that one has one's own local repository to play with, and then merge with other repositories, is enticing to users. Bu how is this different from:
1) Creating a local SVN repository and importing some branches from another SVN repository.
The amount of work to do that in svn compared to the amount of work to do that with git/mercurial is ridiculous.
2) Having one's own branch of an SVN repository as one's own.
That could work, but it'll yield a repository where you have about 2-3 branches per developper (yes, people using git/mercurial often have lots of features/tests branches) that nobody cares about. Also, storing test branches on the public repo is just silly imho. What I object to about the DVCS people is that they seem to assert that
because DVCS has a model they like, where there is no concept of a central repository, that this is automatically superior in some non-practical and perhaps personal way. I do not doubt that DVCS systems may have some very good tools for merging together various local repositories into some other one(s), but what does this freedom really amount to ? The end-user feels better because it feels like one can work separately more easily and then join one's work with others, but in reality a central repository system has the same "tools".
Simply creating a branch and then merging it back was a nightmare with svn. If you typed your command wrong, or did an error, then everyone suffered of your mistake. You then had to correct it in a rush before it created problems for others, etc. With git/hg, when you do a mistake, you simply cancel your local merge and redo it again until you did the right thing, then you push.
I guess I am saying that on a practical basis a DVCS may be more flexible than a centralizes SCCS, but I see no inherent reason for this.
To be honest, I feel that all the people that "cannot see the advantages of a DVCS" are people who either didn't try it, or tried it just enough to reassure themselves it wasn't worth it. Any tool can suck if you're not willing to *really* see what it's worth. Philippe