I don't agree with your criticisms of metrication. Speed in metres per second equates in numerical terms to about half the value in knots. And it would be a pretty dim pilot who could not add or subtract 300 metres or multiples thereof.
Can't speak for the pilots. As stated, I'm an ATCO. And I'll say it again: Forget it. Unless the seperation standard is changed to 1000M. It's not on. A pilot probably has to acknowledge/read back maybe 5 or 10 altitude instructions in a flight (depending on length/complexity of airspace etc), and ATCO might issue 500 or a thousand (or more) altitude related clearances per shift. When the required standard is units of 1000, it's very easy to learn. To have to mentally go through the three times table ( or consult yet another reference flip-chart) each time this is done is just asking for it.
What's the appeal to going metric in this area, anyway? Apart from saving the news media and other interested parties from having to make the conversion themselves?