just to confirm is it right that -Z is just useful for --preset standard or will it also work for --preset 128?

-Z should not be used anymore with recent builds.
Check the recommend settings thread.

But since there is no word of abr modes i bet its not usefull for them than?

Noise shaping 1 is not as useful for abr, because it uses different bit allocation than vbr. There can be advantages or disadvantages, but it's not as big issue as it's with vbr.

Question: Why was -Z removed from the recent 3.90.3 build? I understand the fact that this prevents confusion with --aps, but if I wanted to use this with another command line...

P.S. --apmedium doesn't use -Z, right (because of bitrate increase)? I do seem to recall using --apm -Z with a 3.94alpha build and noticing a speed increase, though... (reasoning behind the above question)

Or I could be just completely wrong and need to be slapped...

You know that 3.90.3's --aps should be the same as 3.90.2's --aps with the addition of the -Z switch? Now imagine doing --aps -Z on 3.90.3, that should be the same as doing --aps -Z -Z with 3.90.2. As far as I know, this would harm the encoding.

Yes, -Z is a toggle. -Z -Z would turn noise shaping 1 off again. Simple: DO NOT USE -Z ANYMORE, EVER, FOR ANYTHING. (With 3.90.3).