From what I understand, quite a bit of work was done on all this, and the main factor is about contrast, as opposed to simply what colour is chosen. For various reasons there was a desire to move away from yellow, not least because (again from memory) after some work had been done it was found that yellow wasn't necessarily the best colour anyway.
Personally I tend to agree with the view that yellow should be avoided, especially if it doesn't even do the purpose that well.
The original Jubilee design I was never overly keen on, though it worked better with the original moquette - as built the whole interior was designed as a package. The moment the ghastly dark blue Tube Lines moquette appeared it made the interior look awful (same on the Northern Line), and the Barman moquette isn't much better in its original form, though some of the versions which use different colours look much better. So on this basis I prefer the grey, though it would have worked better with a different colour moquette IMO. As an aside, there was a reason why the aquamarine was used for certain parts of the original Jubilee interior, it was meant to represent something or other, can't for the life of me remember what!