I agree. Having a community site that complement the help center could be a good thing but only and only if it is done in the right way : it shouldn't compete with the help center (meaning fragmenting the info) but complete it with things that don't have their place on the help center (like some advanced topics).
Having a hardware listing instead of doing PR to complete the help center is the perfect example of counter-productive thing to do.
Defining tags/categories before having content doesn't make sense. It'll just end up by having a site that looks unfinished with lot of empty sections.
Duplicating the info or splitting the community across many different places is usually not a good thing, thus it is important to be very cautious when doing it. It should only be done on purpose and always redirect the visitor to the source for the info that are published there.
Just my two cents.
