betwys, I agree I use alot of SCR's at work. Like you said, the big downside is cost, and sometimes space. I really built this for someone that needs something low cost and simple to hook up. AC is a strange world.
This circuit is just about the same thing that goes inside a SCR, it is really just making the cost less by breaking it down and giving some more control.
I am working on the final version and am leaning towards a separate board rather than working with a shield. I personally love the shield idea, but I know it can strick some high voltage fears in people.