For what it's worth, I think PMBR is worth it.
You will never run out of practice MBE questions if you take PMBR. If the extra money is a real problem, you can buy just the PMBR three day session and you get all the essential books (the blue book and the red book of questions) as if you purchased the 9 day package. (It's 9 days because of the 6 day warm up prior to Barbri classes and then the same 3 day session after Barbri ends). If you take just the 3 day session, it is less expensive and you still get the benefit of a simulated MBE exam under timed conditions in a room full of other highly stressed individuals. With the Barbri simulated MBE and the PMBR simulated MBE you will have a good idea of how you react on "game day." I think those two practice tests really help control your nerves and give you the confidence when you start to hit that "wall" around question 120 or so on the MBE.
One more point about class standing. Although statistically, it's true that a higher law school GPA has some predictor value as far as one's chances of passing the bar on the first attempt, never forget that it's a "flukey" test. There're always a few stories about individuals who were highly ranked and for one reason or another, those individuals failed the bar on the first attempt. I think the best way to approach the bar exam is to study hard and prepare by working old essay questions, using the barbri schedule, taking PMBR, and just hitting it very, very hard. You might as well go into the test with every possible advantage.