Thanks, @Laubmoos and @LLK.
Yes, I often make small adjustments to locate the keyboard (musical or typing) at ‘just the right level’. Or the speakers, if I’m mixing.
The desk is surprisingly stable even with a heavy midi keyboard fully extended (see photo). If you like to pound really hard - barrelhouse style - then you might feel differently. Personally I’m more conscious of latency than physical stability when playing.
Also, I’ve found I can adjust how the keyboard ‘glides’ (whether it wants to reach its full extension, or hang out mid way) with slight changes to the Jarvis leveling feet.
Overall I’m really happy with the tradeoffs.