Christmas Stollen with sourdough instead of yeast?

I'm thinking of making Christmas Stollen this year with a sourdough pre-ferment instead of a yeasted one.  The reason being that, with the expert and generous advice on this wonderful site, I now seem to be able to consistently bake an airy, nutty tasting, golden crusted sourdough loaf, and I'm curious to see if this new skill might be applied to a traditional stollen.  Will it add to the flavour and keeping qualities?  Will it make it too sour?  How much starter do I use to replace the yeast?

Apologies for so many questions but I'm nervous because, if I get it wrong it's going to be a whole other year before I can have another crack, so I'd really appreciate it if anybody has any recipes, methods or experience to share that might guide me.  

Many thanks.