[ghuntley]

Go with what you know - get out there and test/validate the concept instead of learning another technology.

FYI go check out BizSpark which is a pretty amazing program - 60k/yr of hosting credits and whilst you continue to host on Azure there are no licensing costs. Architect your software stack properly using repositories/interfaces and develop against these if you are worried about lock-in to Azure - done correctly it will allow you to adopt a hybrid approach of mix and match of offerings between vendors.

Some basic considerations:

a) Ability to find quality .NET talent in your local area? (It's not hard to stand out and attract quality developers in .NET simply by adopting a strong open-source usage/contribution policy. Using languages such as F# behind the scenes will make you stick out even more.)

b) .NET makes hiring simpler - you'll obtain the opportunity to use and reuse the same language/code on the server-side as on the client side. Using Xamarin means you don't need to hire a Android mobile guy to do the app, then hire a iOS guy to redo the same project in another language. You get product/feature release parity for essentially free.

c) Are you in this for the long haul or are you aiming for exit? If exit consider the technology stack of potential acquirers.