As to whether they're worth the effort, you have to decide that. Although better performance is generally predicted, you'll never know until you actually experience the same plane with, and without the devices.
In recent simulator tests of my sport jet, (
http://homepage.mac.com/mikejames/ne...t_x-plane.html ) the results were remarkable. Flaps and speed brakes produced the desired results, but not "surprising" results. However, the biggest difference was with the leading edge flaps. They made the stall/snap behavior a thing of the past. At some point in our flight testing, I'll be building these on the actual model, and then we'll know. Simulator results have been reasonable, but not perfect, for other designs of mine in the past.
In the meantime, you may find this set of pages helpful. It has drawings and animations of both actual and RC-scale mechanisms, which you might choose to experiment with.
http://homepage.mac.com/mikejames/ne...ift_index.html
If you incorporate them, please come back here and let us know your results.
Have fun!