looked at them...looked like it was one more thing to go wrong/have to think about to me. A regualar peep your eye naturally lines the pin up in the center of...not so with this.
Looks to me that the only difference in the String Splitter is that it is bigger and not an enclosed circle...The issues it claims to resolve, I've never had any way...I'll stick with my peep...no need to change what works.
Ive got one on my switchback and like it. Works really well with glasses and low light conditions. I think they come in 3 different sizes I have the biggest one the hole is about the size of a nickel.