"3 out of 4 bullets are headshots with an r99. never see pc players hit those kind of headshots from mid range. weird. only from aim assist". This is just not true, you see it every game when watching the ALGS or any good streamer. Aim assist does not reduce recoil so the player would have had to control that really well so they were probably just a good player. TSM Imperialhal plays with a controller player on his team so doesn't seem to have a problem with it. TSM also played a tournament with controllers and won ( they won loads with M/K before) but have gone straight back to M/K. As professional players that make their living from playing I would think they would have stuck with the input method that gets them wins and more money. I would infer that most of the pros are ok playing with controller players as I don't really hear of them complaining about it to ALGS organisers. Here are a couple of videos you might like to see.
1 - fpsSHIV using a controller (https://www.youtube.com/watch?v=roU3-FtAWo8&t=358s). Obviously not for the first time and clearly missing lots of shots and not 1 clipping people. Only have to watch the first 2 mins
2 - again shiv 1 v1 a controller player that insults him in his stream. This is hilarious irrespective of which side of the aim assist argument you are on.(https://www.youtube.com/watch?v=x60o3k9QY8U)
3 - the Gaming merchant talking about aim assist and cross play (PC player). He has also made other videos about the subject and has ranked up to masters on PS4 to experience controller play in a later video (https://www.youtube.com/watch?v=s6O6ACH1XuI&t=1s). the summary starts at about 13:25.
This is my opinion and I have played on both PC (all the way back to UT99 when I was at uni) and Xbox. I don't have a problem with it and I must be really bad because I miss lots of shots and hardly ever 1 clip someone. I now prefer to play on xbox for a number of reasons that include not aggravating RSI and also not getting frustrated at trying to google solutions for why games just stop working all of a sudden (and the solution is deleting some some random code that has appeared in one of the system files for the game). I have lost days trying to fix some games and that just doesn't happen on xbox.
Hope you get something from the videos especially the second one.