I agree with the feedback Tim received from Eric at OJ. I have run the 5 blade on my 45 and noticed a huge top speed drop off, more than 5 MPH. It performed about the same on hole shot as my current 4 blade but the 5 blade did maintain better speed control, less RPM jumping during waking and surfing. The best all around performance prop I have tried to date is the OJ 14.75x15.5. Best hole shot and top end.
If you don't care at all about top end speed and are going to run tons and tons of ballast then maybe the 5 blade is for you, otherwise I would stick with a 4 blade.
2008 X-45 Pro Tour Red and White