We are starting off a new project with sitecore as our CMS. I was thinking of using Sitecore as the Content Authoring Tool and use ASP.net MVC as in the Content delivery(CDA
They sure can be mixed, and I sure do see the value of it :)
No native functionality is lossed with the method I describe in my blog post here:
http://www.chrisvandesteeg.nl/2012/02/26/sitecore-mvc/