I have been playing Bulletproof blue soft for about 7 months now. I noticed a bit of mushrooming on it, by feeling with my fingers it is just noticeable. I took some calipers and measured in two locations, first right by the ferrule, and secondly, at it's widest spot. The difference is approximately 10 thousandths of an inch. Also, when striking the cue ball I have been leaving some pretty aggressive chalk marks on it. They were able to be cleaned up with some Aramith polish, but seemed noticeably worse than with leather tips. I have been using Master chalk so that shouldn't be a problem. Both of these issues seem to surprise me, I never thought the tip wouldn't mushroom, although it is not a great deal, it still has mushroomed a little bit. The marks on the cue ball are a bit disturbing because eventually it will scratch it up. Striking the cue ball with various shots you can hear a difference in sound, the synthetic tip gives more of a ringing sound then the standard leather tips do. I probably play 4 hours a week on my home table. I've attached a photo below, and the mushrooming can be seen easiest on the bottom side of the photo, but can be seen on top or bottom if you look carefully.
