The MPAGB is the top PAGB distinction and requires twenty pictures approaching international exhibition standard. Therefore it makes sense to submit pictures that have gained acceptances and awards in the FIAP salons, which is what I did for my slide panel. So you might say that my slides were "road tested" beforehand.
However, this is no guarantee of success and my first attempt at the MPAGB failed by quite a few points. Some slides that had been quite successful in exhibitions failed to reach the "par score" on the day. For MPAGB you need to score 450 points out of a possible 600 and this averages out to 22.5 points per image. In other words, you need five of the six judges to score 4 points and the other judge to give at least a 3 just to stay on track.
For my second attempt a year or so later I changed about a third of my slides and luckily this time the judges were more in tune with my work. As you will see from the above my slides were a mixture of still life and creative images, with a couple of "straight" pictures thrown in for good measure. For the PAGB awards it's best to put in a variety of subjects and not all in one style, so it's the exact opposite to the RPS distinctions. Also worth noting, your slides or prints are on view for a very short time, so the judges are making almost instant decisions. So simple pictures with lots of impact are probably best.
Finally, don't be discouraged if you fail your "M" at the first attempt - it's well worth striving for.