no its not accurate! you yourself can predict if your will go pr 5, coz your the one how work on that site since from the start right?
from the term itself "predictor" meaning just predicting, meaning not sure. different PR tools uses different methods in determining rather predicting PR so they might have different results,. better yet wait for google PR update as its only google who really knows it
PR prediction has now become much like tarrot reading. You don't know how the result is arrived at and if the result is accurate enough.
these tools are just hype or linkbait to get uniques to the owners site. forget about wasting time on them and keep working hard on your seo/sem and you will be rewarded
again and again and again. Unfortunately most people worry themselves most with PR than with the website content. If you have good content you'll have regular visitors, which won't happen if your website has a "fabricated" PR.
It is called a predictor for a reason.....it is supposed to predict not give you a definite answer and if you did not pick up by now no they are not accurate
I had one my site predicted PR 4 but after update it was just PR2, so I don't think the tools aren't accurate.