Yes and no. The point is that you're not retroactively billed for licenses you got while in the program. Believe it or not, a lot of people seem to think that it's just a delayed payment program. Yes, if you're designing a system that's going to require more than 6 servers you might end up paying for a license. Windows Web Server runs ~$470. But for many businesses, if you're using >6 servers you're likely going to be deploying to some cloud hosting solution, or possibly using a shared hosting service (which would include licenses).
It's a tired example, but StackOverflow really is an example of a startup that got a lot done with very few devs or servers and launched a very successful business. Also key is that you can mix and match technologies as you want, something that the StackOverflow used very intelligently (e.g. Microsoft server fronted by non-Microsoft reverse proxy, etc.).
> if you're designing a system that's going to require more than 6 servers you might end up paying for a license
Even if you don't have to pay for the first licenses, you'll pay for subsequent upgrades. And designing for the Microsoft makes it harder to migrate to anything else - that's probably why Microsoft invented BizSpark in the first place.
Stackoverflow shows you can get a very significant audience on a half-Microsoft stack, but they have a lot of interesting (as in "different from the ones I have") server management problems because of that. That makes their podcasts much more worth listening.
Considering that most startups fail for reasons other than technical (running out of money, lack of traction, founders moving on) I don't think any correlation will be that meaningful. It will be interesting see a plot of the type of the startup (social, b2b, retail etc) versus the stack though :)
I am not so sure technology stack is entirely unrelated to failure rate. The stack you pick may influence iteration speed, hosting options, developer availability, uptime, reliability, security and costs.
Twitter would have failed had their scalability problems persisted.
In fact, I remember "Six Degrees". It was more or less Facebook, but in the late 90's. IIRC, they ran Cold Fusion on Windows.
Another consideration is that if you do succeed, you can partner with MS, which provides some cost savings with MSDN licenses. At my last start-up, we authored several white papers about our solution and how it meshed with MS's toolset, and we received significant discounts with licensing.
It's a tired example, but StackOverflow really is an example of a startup that got a lot done with very few devs or servers and launched a very successful business. Also key is that you can mix and match technologies as you want, something that the StackOverflow used very intelligently (e.g. Microsoft server fronted by non-Microsoft reverse proxy, etc.).