Some conclusions:
vcf (downloads) declined despite forums and articles.
forums made positive impact ~5times for U++, while ~2times
for vcf.
vcf articles had "short lived" small impact and didn't help to restore downloads peak.
if you don't have quality of your product and community attractivness you will lose users to competitors fast and gain from articles will be "short lived" ...
P.S this doesn't mean that I'm against articles. I just say that if a product (including community as a product) is rubbish, users vote with their feet (just leaving). Or you have a lot of "download passengers" but not users. My opinion is quality. It's better to have less downloaders but to make everyone (ok 80%...) a "resident long-time quality user". I suggest to concentrate on creating "attractive quality community services" to be beneficial (or profitable) for its "quality residents"...