Hi,
I'm not the most experience pen turner but i tried PSI, Berea and CSU kits. My kids carry 24k slim in their school bags and the only 24k kits that did not cause problems in 12 mounths are the PSI one. Like Alamocdc, i gave away over 75 slimlines in the last 12 mounths. The so called upgrade gold came back with plating worned out in 4 mounts. All the PSI in the field are still ok.
But PSI have some terrible kits (specially when threads are involve) but IMHO their 24k plating is the best around. CSU have the best high end kits (again IMHO), but they apply their higher price to all their kits and their regular 24k or 10k(that don't really last better than the 24k)are not better than PSI. As for the other plating (platinum, TI ect) they are all the same quality and never had any problem with them . I use daily a TI euro from PSI for over a year and it's not even scratch, same with my wife . So i guess that people had problems with PSI in the past and just put it on the blacklist.