I use both TP & EasyWDW. I also take in to account that their predictions are exactly that - predictions. Even with all of the historical data, etc. the one thing we have seen lately at WDW (at least from what I have been reading on the DISboards this year) is that crowds are a lot more unpredictable than they used to be!
We make our plans using info from both sites and hope for the best. If it ends up being crazy busy, we adjust our plans as needed and go with the flow.