unibikeling, you should check Hugos post in your other thread. His design is brilliantly simple and if you had the arms that make the triangle pivot at the center points of the gears (eg. directly behind the cranks and on the wheel axle) you would not have any changes in chain tension and also you would not have any rotation of the cranks or the pedals with the compression of the suspension.
His design fixes the two biggest problems with yours and does not require much for extra parts. I urge you to consider his design as the vertical chain and dynamic tensioner that you have now will only cause you headaches.