Two thoughts: 1) The money they spend on a windows server to run your application on is money out of your pocket. 2) If you will support plugins like wordpres

Two thoughts: 1) The money they spend on a windows server to run your application on is money out of your pocket. 2) If you will support plugins like wordpress, trac, etc, you'll have an easier time creating a plugin ecosystem with open source tools. Then again, I'm biased since I work in a linux/java/ruby shop. I'm assuming that you plan to have your customers install the application. If your target customers are the makers of software as a service, why not sell them your software as a service?