maybe is just funny to ask this and put it this way, but... how long is the course of a key when pressed to the maximum?

i mean, how many milimeters (would you be kind enough to measure that!?) the key goes down when press it?
for instance, i didn t like the course of exr5 from roland. can you comment please?
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Yamaha S770, Studio One 3, EMU 0404USB, ESI, ATH, Dell. And others.