I’m a rock keyboardist/pianist, so I think I may be approaching this question from a different angle. I played classical music for years (very little jazz), but I’ve been away from concert piano so long that I almost might as well have never played.
I can tell you that for me, playing with a lot of black keys requires a bit more concentration on my part, simply because rock songs tend to be written in keys that don’t require a lot of black keys (C, F, G, Eminor, A, etc.) Especially becauseboth of my bands lean heavily away from more “difficult” rock like The Police, Elvis Costello, etc. (we play a lot of punk and rockabilly in one band, a lot of New Wave/early goth in another).
That said, I’ve been teaching myself to play a lot of Peter Gabriel, Police, Elvis Costello, and others who don’t use what I consider “rock standard” keys. It’s really good exercise for my fingers and my brain. This song: Costello Elvis - Olivers Army Chords | Ver. 1 starts out really easy for me, but after the key change at the end of the bridge, I get a little lost. I’ve had to really practice it hard to effect the key change without stumbling.
That’s just me. I do not consider myself an amazing piano player, just a mediocre one who lucked into a really good gig.
I can’t give any complex riff examples, but to get really basic, B flat major is very different from most other keys for playing a simply major scale. You pretty much have to start on an off finger whereas in most keys you ran run off a quick scale starting with your thumb. Hence, a quick upscale run followed by a chord could be awkward in B flat but easy in A, E, D, F#, etc. (Or, for that matter, there might be some specific series that would be made easier by being in B flat).
I’m surprised by this. Then again, as I said before, everyone is a bit different. I like soloing in E or A blues. It’s not my favorite, and I agree with you that G is the perfect piano-guitar compromise key, but I feel at home in E or A. I lose the minor third -to-major third slide that I like, but I still have the augmented fourth/diminished fifth slide that I do all the time, especially with sevenths on top. The keys of C and G have both of these, which is why I like them, but C feels especially “vanilla” for some reason.
For whatever reason, I don’t like the tonic or fifth being on black keys.
As a classically trained pianist I also started with a pentatonic scale using all the black keys. It is easy and fun for true beginner, especially with improvisation. There is very little dissonance if you stick just to the black keys. Though scales started with C major.
Frederic Chopin developed a system where beginning students started with the B major scale, the last scale they learned was C major, which is basically the opposite of the usual method. He felt B fit the fingers better.
I believe it’s a matter of one’s Level or ability combined with the tempo and key signature and rhythmic feel of a song. I don’t mind playing jazz style comping in LH but find playing Johnny B good in Bb more difficult with the RH, as I am trying to do straight eighth note patterns on narrower keys.
