Kurt Grandis carried out an awesome Django vs .NET experiment at his company:

Almost two years ago I was in a rather unlikely situation in that I was running a software engineering department containing both a C# team and a Python team…It slowly dawned on me that I had a perfect test bed. Here we had two teams using different technology stacks within the same department…they shared the same development processes, project management tools, quality control measures, defect management processes. Everything was the same between these groups except for the technologies. Perfect! So like any good manager I turned my teams into unwitting guinea pigs.

With the result:

We found the average productivity of a single Django developer to be equivalent to the output generated by two C# ASP.NET developers. Given equal-sized teams, Django allowed our developers to be twice as productive as our ASP.NET team.