Sibilance can be a combination of several things, aggressive high end of a mic, a bright voice with lots of "s" type sounds, adding EQ in the 5-8K range. When I'm trying to get a mix, it makes a big difference what I'm listening on. If the speakers are kind of dark, or lack extended frequency response, you might boost frequencies to make up for what appears to be missing. If the speakers are bright, you add bottom and cut highs, which then makes it dark on other system.
As for AKG's recommendation, if you don't have an effective pop filter, then you need to avoid going straight at the mic, especially if you are close. The plosives will pop out at you. If you look at a many announcers, they will often have the mic about nose level and pointing down at the mouth. That's because the natural flow of air is usually down and outward, not up. You get the proximity boost that announcers like, without the pops.
A lttle trick, if you hang a few shreds of tissue paper at the front of the mic and watch if they move, you'll know if you have an issue with air hitting the mic. Good pop filters will alleviate a lot of the problem.