My experience of split image/prism type screen vs 42204 (clear, just crosshairs):
I find it MUCH easier to focus using the 42204. I sold my split image screen a long time ago and have the 42204 in all my Hassies.
The subject will kind of pop into focus with the clear screen, and I can also sometimes see the faint texture of the screen when I'm in focus. And it's nice to not have distraction of split image/grid.
I use a PM45, with the built-in diopter adjusted for my eyesight. For a while I had to use the accessory diopter (which you attach under rubber eyecup on PM45), because the built-in one didn't go as far as I needed. But now my eyesight has changed, and the built-in diopter is enough. The accessory diopter is extremely hard to find, BTW.