Which concert are you talking about - what year? If you notice, he has transposers and other techno gadgets that he uses on his piano to mimic other sounds, ie a keyboard. Maybe that is what your friend means. Or he has used side keyboards on certain songs, like Pressure which is what is true to the song as he originally wrote it.

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joelsgirl

If you look at his album sleeves you will see he is very versatile with instruments and has used piano, keyboard, organ, guitar etc.
He was originally trained on piano, but I think he could get a good tune out of the kitchen sink.

Jools