PFP exhaust is good for high end/high rpm like flatwater combos. The TNT exhaust is good to tune in any RPM range although I think I have seen people with the xscream motors leaning towards the Power factor because that is where the motor likes to run. If you are racing or surf it is a no brainer to run the TNT, if you are running flatwater then more thinking might come into play but biggest thing is the motor you run and what your builder suggests for the package.
As for cracking you have more material to crack in the PFP so I am sure that issue still exists, I have a TNT V3 system for my 900 and 1105 flatwater boat and love the system. Never any cracking issues since I have had it. I have seen people have issues when they use different manifolds or they do some really hack work. Install it properly and you shouldn't have an issue with either system. Tim is great to talk to and if you are running his pipe he really goes out of his way to help you get dialed in. I spent my money and will in the future because you are buying more than just a pipe when you purchase TNT.