A story told to me by a piano teacher:
Liszt was hired to do a recital in a small town. We he arrived and saw the piano they had for him to play he stated "It is too small, but I play it anyway". The story concludes that his performance was, of course, magnificent.
Moral: It is the player more than the instrument.
As pianists we seldom will get to chooose the instrument, we have to take what the give us to play. I've played on some really horrible instruments. Of the moral of this story expects the piano to be functional. No broken keys,strings, pedals, etc.
But another story that I believe to be true about Keith Jarret for the recital that was recorded and released as the "Koln Koncerts". The story goes, he drove to Koln to perform at an opera house that never allowed non-operas to be performed. To get them to allow Jarrett's recitial, it had to be scheduled for midnight (it was standing room only anyway!). We he arrived, the piano he requested, Bosi 290 I think, was not there. A smaller, rehearsal piano was provided, another Bosi, maybe 190, that needed maintenance. The story goes the pedals weren't working correctly. Jarrett wanted to drop the recital, but in the performed, was recorded, and the recital was outstanding. The recording is a famous album around here.
Again, the pianist is more important than the piano. (unless it's total PoS!)