Git may be trendy when moving from Subversion, but having read about Bazaar as well, I like the fact that Bazaar provides (more or less) the same facility for client-side commits and rollbacks as Git does, but Bazaar also provides good support for also doing updates and commits with a remote Subversion server. It sounds like the best of both worlds, so I'm going to try it out, see how it goes.
As with any UML model, lots of details to get right. To the best of my knowledge, no-one else has yet tried building UML message models using the 2009 version of the ISO 20022 standard (for modelling banking/finance messages in UML). The 2009 version of the standard is currently out for vote as a committee draft, so it isn't approved yet. The approved version of ISO 20022 at present is the 2004 version, which was the first version.