I wonder what's so terrible about Klavarskribo? I imagine... it doesn't conform to present standards and availability issues?
Well, it's not what I meant, but that is also an important point which cannot be ignored. It is difficult for the market to support different competing formats, as we know from what happened to Betamax, where commercial pressures were more powerful than technical superiority. I think it is widely acknowledged that Beta was superior to VHS but still it lost out even though it already had high market share. KS has neither high market share nor technical superiority, but survives in a niche market of people who have been fooled into thinking it will make their life easier.
Yes, I'll get to that later.
Zebra Problem: 1) Its Kbd layout is C-maj only.
That's not really true. You might as well say it's F# major only. I'm grateful to Richard for mentioning Irving Berlin, who apparently could not read or write music and played by ear. He only ever played in F# major because that was easiest for him because it uses all the black keys, which for him were easier to find and easier to strike. If he wanted to play in a different key, he used his transposing piano so that he could continue playing in F# major while sound came out in whatever key was required.
Anyway, F# major is a particularly easy scale to play, much easier than C major, because it makes you use the appropriate fingering intuitively. In C major you have to force yourself consciously to make the thumb changes in the right sequence (not that it matters if you don't, but if you don't you get into bad habits which will catch you in other keys).
2) Its black keys are only 1cm wide and it takes ages to get my brains programmed to that narrow error margin;
This is a job for the fingers, not the brain!
If you're talking about relative error margin (where one hand has to play several notes together, and if one finger is in exactly the right place, the other(s) might not be), then you can train your hands so that the fingers involved are the right distance apart (which will be a whole multiple of 1.37cm), but even with Janko you should really do that anyway, and aim to hit each key in the middle if possible. If you're talking about absolute error margin, for long distance leaps, then you must agree that the black keys are of immense help because the hand can feel its place before it plays.
Talk of error margin raises an interesting point, by the way, namely that on the piano's white keys the "best" landing point for the fingers to aim for is not always the middle of the key. You need only to look at the key shapes to realise why. The ideal place to aim for (from the point of view of training the fingers to use the same distance multiple everywhere) is the centre with respect to the 1.37cm all-key spacing. But of course the white-key spacing is not double the all-key spacing, it is 12/7 of it, or about 2.35cm. The white key error margins are asymmetric. This is merely a consequence of how the geometry must work out. But you will just hold this up as another disadvantage!
whereas Janko keys are all equally sized at 2cm width; i.e. allowing for a generous 2cm error margin!
It's much less! The error margin is the maximum amount by which the centre of your finger can be off target (the target being the centre of the key) before there finger risks hitting any part of an adjacent key (the problem is not just hitting the wrong key instead of
the right one, it is hitting the wrong key together with
the right one). The error margin is half the key width minus half the finger width plus the inter-key gap. The key spacing should be 2.35cm (so if your keys are 2cm wide you must have a generous 3.5mm gap), and let's say your finger width is 1.4cm, so the error margin is 6.5mm
Now, to get back to what you said about black key error margin. With raised keys the margin must be calculated differently. How far off-target can the finger be before it risks to fail to operate the key in question? Well, an easier question to answer is how far the finger needs to be off-target before it will definitely fail to operate the key, and the answer is half the key width plus half the finger width, so that would be 12mm. Obviously we need to deduct an allowance to ensure we do hit it, but you can see that the margin is going to be about the same as for your Janko keys, and probably even a little more!
...if you are going to have lessons, you need to learn zebra, and if you want to learn Janko, you can't have lessons.
Well, that's right: many/ most of the exercises required in a zebra Kbd tutor mightn't apply, because of Janko's simplicity.
The problem isn't so much that many of the zebra exercises are not relevant, it's the lack of Janko tutors and of teachers with Janko expertise.
I'll say more about notation at a later stage, but KS notation is just so deficient in several important ways, that it will not do you any good in the long run.
KS is being taught at the conservatory of music in Holland.
Are you sure? If you're referring to the KS Institute, I don't think that qualifies as a conservatory. If they're really teaching KS at conservatory, it must be either because they are trying to show everyone how bad it is,
or because they are catering to the niche organist market which happens to be concentrated there.