As someone who sold a startup which was written in .NET (C#) I can tell you that it scales very well and is a great choice for a tech stack if you're competent in it.
I would also offer you the following advice in reference to the major drawbacks of choosing it.
1. Hiring good .NET devs is HARD there just is not a major interest in learning it at this point so most of the young guys are focusing their attention on ruby and python (I am going with Ruby for the current project I'm working on now too!)
2. Make sure you have a very good relationship with your co-founder because from my experience many of the .NET devs who are "lightning fast" are also those who refuse to comment the code well and take the road less taken in reference to their programming styles. This is not necessarily a bad thing just something to be aware of, because if he is not around to school future devs on the code base you could be kicking yourself later.
3. Carefully buy the licenses you need as you need them, you can work out deals on licensing even after you have ordered others seperately.
4. Try partnering with a company who is a BizSpark Network Partner as it will help considerably with cost and give you a great foot in the door with Microsoft if you do begin to scale in ways you hadn't planned for.
I think you're making a fine decision. Going with the masses is not always the best decision and choosing another language only because it's the hip thing to do is usually not a good position to put yourself in.
I would also offer you the following advice in reference to the major drawbacks of choosing it.
1. Hiring good .NET devs is HARD there just is not a major interest in learning it at this point so most of the young guys are focusing their attention on ruby and python (I am going with Ruby for the current project I'm working on now too!)
2. Make sure you have a very good relationship with your co-founder because from my experience many of the .NET devs who are "lightning fast" are also those who refuse to comment the code well and take the road less taken in reference to their programming styles. This is not necessarily a bad thing just something to be aware of, because if he is not around to school future devs on the code base you could be kicking yourself later.
3. Carefully buy the licenses you need as you need them, you can work out deals on licensing even after you have ordered others seperately.
4. Try partnering with a company who is a BizSpark Network Partner as it will help considerably with cost and give you a great foot in the door with Microsoft if you do begin to scale in ways you hadn't planned for.
I think you're making a fine decision. Going with the masses is not always the best decision and choosing another language only because it's the hip thing to do is usually not a good position to put yourself in.
That said, Good luck with your startup!