We need to develop quite a powerful web application for an investment bank. The bank IT would like us to build it on top of the SharePoint platform
SharePoint is a lot of work and with that amount of users I personally (and being a SharePoint developer) wouldn't bother.
I would go down the ASP.MVC route in all honesty and not because it's new and the latest buzz technology. I would use it because it's hands down faster. This site for example is written in ASP.NET MVC and it handles all these requests per day on I think 3 servers. 2 front end and 1 database. Correct my if I'm wrong with that.