As David Satz already mentioned, the omni and figure-8 settings of the KM 86 don't work as specified in close proximity to a sound source. When using the km86 in Figure of 8 only a few inches away from a source, it probably reacts more as an omni with a lot of proximity effect than as a figure of eight. Sure it will give a very special sound.
I would not call the patterns that very uniform, the figure of eight is on its side very sharp, that it is not useable for MS stereo. At least when you don't like a sharp sound, and highend roll-off when switching to mono. Lately I have worked several times with the KM86/76 in MS mode, and it was very dissapointing.
The big advantage of the KM86 is in the fact all patterns have the same low end response, something you will not see with small single membrane capsules or large membrane double membrane capsules, but you pay it off with a very inconsistant polar pattern for the high frequencies.
Klaus is right, the extra grid makes it less sensitive for pop sounds, but you pay it with a more rippled frequency response, so dips and peaks. I doubt if the KM86 is less sharp than the KM84. Both are very universal microphones. Purists would probably choose for the KM84.
Schallfeldnebel