OK, only 800 runners for the PPM, but maybe?? the forest service would allow additional runners if they were shown a plan to reduce crowding on the trail.
Chip Timing. Makes things easy, but I think it would work even if chip timing failed. The starter fires his gun for the initial start, then fires his gun exactly at two minute intervals thereafter. For the PPA, 120 runners would start every two minutes. With only 120 runners in each wave, all runners in that wave would cross the start line within a few seconds of one another. No runner would be penalized more than a few seconds if the timing mat did not pick up the runner's chip. You do need to determine when each runner crosses the finish line. I think (not sure) that a camera is installed at the finish line as a backup to record when each runner crosses the finish line with their time.
Registration Process is simplified. No need for two waves. No $130 penalty for signing up for the wrong wave. No need to force X number of runners into wave 1 and Y number of runners into wave 2.
Forced Separation Times. Crowding is worse near the top of the bell curve (average finish times). Multiple waves force separation between runners with the same expected finish times where it is needed most.
Running with your peers. This is a good thing. It should prevent a lot of unnecessary passing and bottlenecks caused by a runner who goes out too fast and finds himself out of place especially in the Ws. It would also serve as pacers for first time runners.
PPM Registration Fast Fill Times. Too many applicants, too few slots. The obvious solution is to tighten up on the quals, but the answer has always been we need the slower runners (and their $$$) to spread out the field to prevent overcrowding. Well, multiple start waves have the potential to prevent overcrowding and make the race more competitive. Will previous PPM runners need a finish time of 9:30 or 9:00? Will the Marathon qual go to 5:00 or 4:45? How about the older runners who still like to run with the pack and the challenge to them is probably more meaningful than runners in their prime. When I ran my first PPA in 2007, there were no qual times.
Ranking the multiple waves. How do you slot previous PPM finish times with Marathon times. It gets more complicated for the PPA with GoG and half marathon times included. I think the race registrar would have a way to do this.