With open source software money usually spent on adaptation. And this adaptation often done by local companies. So in this particular case instead of paying microsoft and usa goverment, munich government will pay local german company of trainers who will explain how to use particular open source software. Another local company will develop custom integration with whatever CRM government have and hopefuly part of this code either as patches or modules will be contributed back to community.

I totally sure their decision is right in long term.