Focussing screens

Hi, with a keen intent to use more manual focussing (as I have a number of MF lenses), I stumbled across the fact that you can replace your focussing screen for a brighter version, ala the ones at Katz eye optics.
http://www.katzeyeoptics.com/cat--Nikon-DSLRs--cat_nikon.html
Anybody here had any experience with these? Perhaps on a D70 or D200?
http://www.katzeyeoptics.com/cat--Nikon-DSLRs--cat_nikon.html
Anybody here had any experience with these? Perhaps on a D70 or D200?