Slotted spark plug holes

[RotaryDane]

Saw this on youtube a while ago and it made me wonder.. http://www.youtube.com/watch?v=m3pCLjHZmhMAs far as I am told the offset combustion cavity does not yield much benefit, Mazda have already toyed around with the idea, but the slotted spark plug hole might yield better milage and cooler exhaust. But what do I know? What is the veterans take on the idea?