What they SHOULD have told you that Bosch's test indicate 3 micon or greater solids in the fuel severely compromise the integrity of the HPCR system. Then again, broadcasting that kind of information in seriously large part of their sales market with the kind of lock there is on fuel production in this country is a good way loose a major portion of your business.

THAT is the real "go figure" in all this. :-laf
I believe if you talk to the injector rebuilders most will postulate a major contributor to failure is lack of filtration and lube. Etching seats is a pretty common problem. While there are seat failures due to the constant hammering and metal fatigue, there that type of damage does not occur in the nozzles also.
In some cases, electrical malfunctions can also be traced to lack of filtration in some cases as the whole filter is lubed and cooled by the fuel. A plain dead injector is another problem but those are relatively rare.
There is enough info and plausible theories to suggest that extra filtration down to 2 microns is extremely beneficial. Considering the cost of an AirDog, FASS, or a GDP system in relationship to an injector rebuild/replace, what more could be needed? Considering what we will lay out for turbos, cluthes, TC's, etc, even thinking about extra filtration is riduculous. EVERYTHING, power, reliability, lifetime, etc, starts with the fuel. We wouldn't dare ignore air an oil filters why even consider shorting the fuel filtration?

My . 02