I have built and installed the Super-PID controller for my DeWalt DWP611 router on my Shark Pro Plus. http://www.vhipe.com/product-private/SuperPID.htm
The Super-PID controller is a closed loop router speed controller. It comes as a circuit board and accessories that you have to build into an enclosure. It permits you to run your router as slow as 5,000 RPM. The result is much less noise, and better cutting.
I would rate the difficulty of completing this unit as 8 on a scale of 10. It certainly helps if you have had experience doing electronic wiring. The instructions are pretty complete. You will need to provide a box, jacks, connectors, and other parts. The router has to be modified to add a speed sensor. Instructions are available
I hacked the NWA controller by adding a solid state relay. I mounted it above the one in the controller and wired the input in parallel with the existing solid state relay. The output was wired to a jack for connecting to the Super-PID. http://smile.amazon.com/dp/B009AQN9CQ/r
My router is much quieter at all speeds, and the slower speeds permit chip loading as recommended.
Good judgement comes from experience.
Experience comes from bad judgement.