I have had the PDM since mid 2011 on my 05 Mastiff. So far no problems and would say about 12k miles on it (would be more but I am overseas allot).
Have ridden it in rain, cold, hot, and all conditions. For me it was a pretty cool installation with no major hick ups.
Do not know if it will last forever or quit the min I start it up nest time, regardless I am not hesitant about getting on the bike and riding, be it 10 miles or 5k miles.
The safest bet is to go with a standard old school rewire, but that take some changes and a few dollars more. Still that is the most proven and always will be. On the WP many have had good luck with it yet I also see more and more issue coming up, IMHO it is just as risky as the old EHC and possibly the PDM. As far as WSW goes, Curtis has been working on it for awhile and I am sure that it will be a good unit. That said it will be new also and will take some time to prove itself.
IMHO anything other than old school is a carp shoot including PDM. Seems every time a new EHC replacement comes out, for many jump on the wagon and many have issue later on. Time and mileage are the true test and not sure I would jump on something right off the bat until such has had a great deal of time in installation and mileage from real riding with exception of old school re-wire. Some have installed a few other types also, do the research and decide, but be aware it is still always going to be a concern for a few years until all have been proven long term.