sweelinck +1, I'm really glad to see this noticed.
Some makers (like Schimmel I believe) try to make up for longer keysticks (IIRC the Konzert series, which is supposed to have concert grand length keysticks) with wider "tails" and shallower bends.
And keystick lengths vary SO much among acoustic pianos, I'd have a hard time picking a single length as representative. Many (most?) grands also have asymmetric keystick lengths, for the hammers to reach the right strike point for a given string speaking length.
Which adds, even though uprights don't sacrifice on soundboard length for keystick length, they still have optimal strike points, and have to adjust parameters like plate size, agraffe positioning, and ultimately, how high the top of the cabinet must be. There are so many overlapping and interlocked considerations in scale design that it really starts to make sense to me why so many pianos look "the same" - you have like 5 key metrics with ideal specs, and changing any one of them affects the other 4. How many different solutions are there that have all 5 in a near-optimal arrangement (and is still manufacturable, serviceable, and durable for decades)?
