XPro1 focus peaking in MF
I think what you're seeing here is longitudinal CA (LOVA).
I guess theres no reason why it can't be used as a focusing aid.
"The only thing that gets in the way of a really good photograph, is the camera"
That's basically it. I've been using that as a MF aid on my Xpro when I need focus to be really spot on. As long as you have something with enough contrast it's there.