We are two developers on the edge of starting new web product development.

We are both fans of lean start-up approach and would like to practice continuous deployment.

Here comes the dilemma - we are both coming from a C# / Windows background and we need to decide between:

Stick to .NET and Windows, we will not waste time on learning new technologies and put all our effort in the development.

Switch to Ruby on Rails and Linux which has a good reputation of fast ramp up and vast open source support. The negative side is that we will need to put a lot of effort in learning Ruby, Rails and Linux...

What would you do? What other considerations should we take?