As a shop, we worry more about reading and resetting codes, system activation functions, and other service related issues. The Durametric is pretty good in those areas. Coding or programing is not something that we encounter frequently, so it is not that much of a downside issue.
The Durametric is not perfect, and in fact may only be 75-85% as capable as the current OEM
PIWIS system, but many of the so called "problems" you see people ranting about on the web are more often than not operator related, and many can be traced back directly to Porsche. Durametric cannot directly copy the functions of the PIWIS system, Porsche owns and closely protects those rights. So they are left to find a work around to get to the same end result in order to avoid Porsche's legal rath. Add in Porsche's penchant for throwing curves at you (some cars have DME's that are totally different from their normal architecture and are even from another supplier; Porsche knows all about it, Durametric has to figure out why a certain car does not communicate correctly while others of the same model year are fine) and problems are going to crop up. Porsche also seems to not totally respect their own demarcation lines on things like which version of the DME, ABS, or PSM software should be in the car because of the model year, and a vehicle that should have a 7.2 DME really has a 7.8. Try and scan the car as the 7.2 it should be, and you get weird or no results; reset the software to 7.8 and everything is fine. Now stop for a moment and think about what can go wrong when someone with little or even no diagnostic experience tries to asses a problem.
Even the mighty PIWIS is not immune to problems, I know of several incidents where Porsche techs could not communicate with the cars, and ended up calling around to independent shops for ideas. I have also heard that there are "tricks" to getting the PIWIS to work on some cars that the techs pass around amongst themselves as well.
We seriously looked at acquiring a legitimate PIWIS unit, but the combination of the outrageous cost structure, the fact that Porsche burned early lessors of the first PIWIS when they released the new system, and the fact that while the lease documentation clearly states that systems leased by "outside entities" (read non dealers) will have "certain functions disabled", you cannot get a straight answer as to what is left out of the system before you plunk down nearly twenty grand a year, we deicided that the shop is both creative and intuitive enough to run with the Durametric Pro system.