Which DVCS work best with Subversion repositories

Subversion works great when we have access to central repository, but sometimes two or more developers work at client where they do not have connection to central repository. I am looking for DVCS that can help us where off-line.

It should:

• cooperate with Subversion repository so developers can checkout before leave, commit locally where off line and commit to central repository when they return
• easy exchange code between developers working offline
• work on Windows, GUI preferred; developers are used to TortoiseSVN

Anybody uses Bazaar, Mercurial, git or maybe something else and can show its advantages and pitfalls? So far I started (really returned to) testing Bazaar with Tortoise Bazaar.

I have tried Git, Mercurial and Bazaar with a SVN repository and I have found that all three work pretty well (when using the their respective *-svn module).

I suggest you pick the DCVS you like most and use that one.

(The modules are git-svn, bzr-svn and hgSubversion)