Well, I usually keep saying that I don't like randomness in game - even if it's fair, and Kongai isn't an exception here, but on the other hand... well, I noticed that this is a part that causes most of excitement when I play. By the way: one thing can be both: 50-50 shot for an amateur and 80-20 calculation for a prof.
Kamikazoo: What do you mean "more than statistically possible"? Hiclic is right (ok, a small correction is needed: debuffs subtract from your current hit chance). Now you would really need to collect results of many, many attacks, group them by percentage and - analyze carefully (mean, variation and so on). It should follow Gaussian bell curve - if chances are fair. But there is always some (usually small) probability for statistical mistake.
Last few words: For me the odds seem to be even. :)