A couple of years ago I was in my peak keyboard phase and was changing my layout weekly. At that time I really wanted something that would analyze which fingers were faster/slower and which big bigrams were slowing me down, especially SFBs.
My layout has been pretty stable now but I'd still love to do some analytics on it. What I would love is a tool that let's me upload my keyboard layout (including layers) and then gives me stats. For example in suspect my left pinky is a problem but that's QA' for me so you wouldn't know that without the layout.