I just bought and installed an S-type screen from focusingscreen.com, and I must say, it is without doubt, the best $90 I have spent in m life (well, camera related that is).
Thanks to all the folks in this thread for all the info:
https://www.pentaxforums.com/forums/pentax-k-5/142241-best-screen-ever-manual...anon-ee-s.html
If you have fast manual focus lens, then this screen is an absolute must. What's in focus just "magically" pops out. No more need to switch into live view and battle the sunlight, lag time and battery drainage.
I was playing with my Revuenon f1.2 after installing the screen this morning and wow. Just wow.
And the installation is super easy. It took me 5 minutes and I was being anal. Even then, most of the time was spent opening up all the parts from their plastic packaging.