QUOTE(Banjogirl @ Jun 18 2010, 03:26 PM)

It's always seemed to me that a good pianist could learn how the keyboard worked and what it could do by using the instruction manual, but someone who had only learnt the keyboard would find it much harder to become a useful pianist.
I once had to cringe when a teacher gushed about how fabulous a keyboard player was in the school concert. He played a melody with two or three fingers against a backing track produced entirely by the keyboard, and didn't even finish it properly. He was the poorest performer of all, but the gtuitars and violins playing what sounded like simple music were left feeling inferior. Sorry, this sounds bvery negative. I have to admit that while keyboards have their uses I hate them being used asna performance instrument as they sound horrid and you might as well record the whole thing and just play it back if the keybaord is already doing 99% of the work.
I know what you mean but a proficient keyboard player is something else entirely.
They will use good right hand fingering for the melody (though the technique is different from piano as the keys are not weighted for one thing) and fully fingered chords in the left hand. In the later stages the inversion of the chord will matter too. They will know how to use the rhythms in an appropriate manner and how and when to change this as they play.
Improvisation is also a part of keyboard playing.
Hopefully a good keyboard teacher would be as careful with good use of fingering as a piano teacher so you wouldn't get the 2 or 3 fingers thing (unless it's a melody with only 2 or 3 notes

).
I do think that in the early stages at least moving from piano to keyboard would be easier than the other way round. Having said that it might not be so easy for someone who hasn't picked up a good understanding of basic chords at least.