Thanks for the responses thus far. I should probably explain a little of my situation. Although, I do have some problems with my back, my biggest problem is with my legs and feet. You see an illness left me with spinal cord damage that limits my strength from my waist down. I also have severe neuropathy in my feet. The bottom line is that I can't stand or walk very long. Being able to work sitting extends the amount of time I can work.
I do see where sitting limits my leverage for some activities. Right now, I pop up and down between standing and a tall stool. The bottom line is that I spend most of my time on my feet working, when stocking, and that limits me to a couple hours a day. When I am making, filing, and polishing mounts, I can do that sitting, and do it for several hours a day. Things really slow down when I have to put the whole thing together.
I really would like to have an adjustable height bench. I will have to look into the adjustable bench designs.