It occurs to me, the real reason to change from one keyboard to another is for the benefit of the performer.
I doubt audiences can tell the subtle differences?
It seems audiences that I play for can tell the difference between PA systems though...sometimes.
Audiences, for me anyway, seem to react more to how I entertain...or volume etc.
I really don't think the audiences I play for...age 40's on up....would know whether I was playing a Yamaha, Korg, Ketron, Casio or whatever.
But I would know the difference....guess that's what counts.
Getting back to the original question which I think was more about whether or not the audience can tell the difference between one KB or another, not whether one is a good entertainer or not, unless you are playing a BOTL KB and switch to a TOTL KB I don't think the audience realizes the difference so much, UNLESS you are someone like Don Mason who plays in one place a few nights a week, and have regular customers coming in each week ... All the audience is interested in is how it sounds, and are they going to enjoy it ... let's face facts - there are people basically performing karaoke and entertaining audiences,even in some upscale restaurants, so does the audience REALLY care about the source of the sound ?!? ...
IMHO, a change from one KB to another is more to benefit the performer, whether it be through
"better" styles, sounds, ease of operation, whatever, ...BUT, those changes may give the performer more confidence, a better feeling about the performance, and may actually led to a BETTER performance, which in turn will lead to a better experience for the audience ... but as to whether the audience appreciates the difference between one KB and another, I seriously doubt it ..