The only lenses I can really say I have noticed any difference with is the 200/4. The PK SMC-M 200/4 outperform the Super Takumar and the 135/3.5 where the Super tak outperform the SMC-M.
Others I have tested is
28 - No winner
35 - No winner
50/1.4 vs SMC-M 50/1.7 - No winner
135/3.5 - Super Takumar outperform SMC-M and outperform Takumar 135/3.5
200/4 - SMC-M outperform Super Takumar
For focusing, first of all, get rid of the beep and the red square. Second get a splitscreen, I use the chinese one for 20$. Lastly preset the aperture and use the M/A switch to open/close. Alternativly, focus wide open and just turn the aperture ring until you get a good time in AV mode.
If you don't want a splitscreen, you will be able to focus more closed down, because the original screen will not black out the same way as the splitscreens does. However, even if it is brighter and you can focus at f11 if needed, you will not get proper focus.
So either have the trouble with dark screens or get OOF pictures, simple as that. And I am sure someone will come and tell you that it is possible to focus properly with the original screen, and they are right, it is possible. But you will have alot of blurry pictures. Thats a fact.