VSTO (dll) for Visio on document level?

[kedas]

If you want to write code for a specific template (.vst), how can you do this without using VBA? (assuming VBA won't stay around forever)

For Word and Excel there seem to be a document level approach but not for Visio?
http://msdn.microsoft.com/en-us/library/ds87aeyf.aspx

Although this application level programming example below makes me think that going away from VBA to .Net is running towards the problems: (at least how they implemented it now)
http://davidjpp.wordpress.com/2011/11/08/deploying-a-visio-2007-or-2010-vsto-add-in-with-visual-studio-2010/

[aledlund]

There's any number of different ways to develop solutions for Visio. Graham Wideman does a discussion in his Developer's Survival Pack on how they can play against each other. I usually start with VBA for sandboxing and then move to .Net (vb.net) for the actual prototyping. The language selection is usually a personal choice, but MS is moving C# and VB.Net closer to each other each year. There is significant overhead in going to .Net, but it brings a lot of tools and support with it. Then there's the choice between VSTO or WinForms :-( You'll find proponents of both.
IMHO VBA will be around for quite awhile. (but I've been wrong before)
al