I see cost is mentioned a lot- but if BizSpark still runs how it used to, you can get a lot of tooling for free to start with, until you grow to where the cost wouldn't have as much impact on you. (http://www.microsoft.com/bizspark/)

I have a friend in the Bay Area who started in .NET, and had so much trouble hiring programmers they scrapped it and started in a more fashionable platform.

I don't know what others' experience is like, but you might consider the ramifications of that potential problem.