By the argumentation on your page, almost none of the electronic data targeted by the data retention directive would in fact be retained if the directive is not also applied to data that merely transit a providers network, given that the vast majority of e-mail addresses in use today are not hosted by "communications providers". If that is indeed an actual loophole, it will be closed quickly if/when everyone realizes that they're not getting the data they expect.
This is in any case a minor point, as in terms of dealing with backup data, it's the two first points of my message that are by far the most serious. And I don't think they're that serious, in that I don't really believe there are any suitable alternatives that are safe enough that you can prevent surveillance based on location, so you'll depend on the crypto, and the combination of the two makes the location of the data rather moot.