Graviman,
Well I finnaly got around to doing some drawings. Although very crued they do give an example of what I am talking about. Unfortunately I don't know how to post a power point slide nor do I have a place to host it. If you are interested I would be happy to email it to you. After seeing it on paper I got excited again and started thinking about making a small spinning model to see how it works in 3D.
As for your question about twin spool engines I would imagine that two spools would be better but it would also add considerable complexity and therefore cost to the engine. In a small helicopter engine I don't think it would be warranted as modern turbines can accelerate from min to max power in about 1 second if you didn't have to worry about the torque limitations on the drivetrain. I believe with a rotor governor you could simply pull collective as you wish while watching the torque gauge and the RRPM will be maintained all by it's self. But again I'm just a grease monkey so I stand to be corrected.
Max