For a really effective revolution, I think you need 70% proles, 28% middle class and 2% upper class.
The upper class components are usually romantics who want to turn the world upside down (anarchist princes, countesses gone off the rails, etc) and can be very useful in funding weaponry and providing safe houses.
Middle class people ARE incredibly useful in an admin capacity - and let's face it, none of us plebs are sending rockets to Uranus in a hurry. Invariably, one of the middle class collaborators completely sells out the movement and becomes eternally loathed in story and legend. On a more positive note, one of them gets sainted Tony Benn status for his/her progressive enlightenment.
Invariably, it all gets crushed by the cops in the end and everyone gets fat and lazy and gives up, but the next generation doesn't have to crawl up a chimney on Saturday morning.