We are about to embark on a large enterprise application. I am seriously considering using ASP.NET MVC because:
Everything I've read about asp.net MVC says that it is able to serve up more page requests than asp.net webforms.
I have some doubts about its stability and security though. Both of these stem from the fact that it's not even released and even with the RC we saw some changes to the framework. I am sure there will be more changes as time goes on and things are found. It's new so there are not really "best practices" out for it and there is a not a wealth of experience out there detailing the small issues or gotchas that you might run into.
I've been using it and it does result in smaller pages and faster performance. But there are so many things I can do in webforms that I have no idea how to do with mvc because mvc does not promote the use of the webforms controls.