I currently examining VS 2010 as an alternative for QTP.
From what I experienced with VS, it looks less convenient and less user friendly, but maybe that's because I'm used to QTP.
Could you tell what the pros/cons for using VS?
Tell me how VS supports non Microsoft development models and projects.
Tell me how QTP supports Microsoft and non Microsoft development models and projects.
Who has a compelling interest in supporting third party development methods and processes?
I ask these questions as someone who has worked for both Microsoft and Mercury at different points on my career path. I have an internal perspective that may not match your own, but I would encourage you to look at the market behavior of both parties as well as their technical capabilities to arrive at your own set of answers.