Some time ago I was testing how a Windows IIS powered backend would perform compared to the current Mono with Cherokee on Linux setup. The graphic shows the measured average response times. The switch to the Windows Backend was done shortly after 10PM. As you can see the average response times were significantly smaller afterwards.
Before there were 2 C3.XLarge Linux instances, afterwards there were 2 C3.Large Windows instances. So the IIS performed better in my setup on a smaller instance.
Since this setup is also cheaper than the set of Linux instances, I am thinking about a permanent switch. I am also going to do comparisons using a different Mono setup. I will test Nginx as well as Apache.