All of my sanders are PSA (except one I use for bowls on the lathe). These are Porter Cable random orbit sanders. I purchased them because the sanding disk were so much cheaper. I was wondering if anyone has used both--this is mainly for large area flat sanding--and if you have an opinion on either. One thing I like about PSA is the sanding pad is firm and allows me to sand up to and over a corner or profile without rounding it or "softening" it up. I am concerned that the H&L system has just enough "give" between the sanding disk and the machine pad to allow it to round off or "soften" up a corner. I'm not sure I have any problems with the PSA system except that occasionally when I lift up the sander the disk will come sailing off the pad. Not a really big problem. I have read that H&L disk last much longer than PSA disk but really don't have any experience with it to know if that's true. Anyway, I was wondering if anyone has opinions about this.