Katz Eye Focussing Screen on D300

I have a number of manual lenses which I would like to use with my D300. The problem is that I struggle to get the right focus; I don't usually carry a tripod with me, and no I can't use live view to get accurate focus. To solve this problem I have now got a Katz Eye screen installed.

First impressions are:

• With AF lenses, Nikon's AF seems more reliable than manual focus using the Katz Eye screen.  This may be because I need to get better at manual focusing.
  
• Even with the Katz Eye screen installed, manual focusing is not as convenient as in my other film SLR cameras. I compared the D300/35mm lens combo with the FM2/50mm lens. The FM2 is easier to focus as the viewfinder magnification is higher.