well but I do not think your or my piano can sound as good as a 6 foot grand in rendering very big pieces. The A flat major Polonaise really would always sound better on a 6foot or bigger grand.
The same as the Rachmaninoff concertos.That is for sure !
This is very true but I was bit surprised how, in some ways, the differences are smaller than I thought between grand and upright. We were treated to a fine pianist letting rip with the Rachmaninov on both the K800 and SE132 we liked and also on the Shigeru SK-7. The big grand clearly was in a different league with power, weight and projection, especially in that large venue, that the uprights could come nowhere near, yet, there was a clear family resemblance between k800 and SK-7 and, power aside, the portrayal was much more similar than seems reasonable. The Yamaha was by comparison less convincing on a piece of this scale but it is a very fine piano, if as expensive as some European models. It's strength is I think what Yamahas are mostly criticised for and that is its treble which does have a sweet quality underlying the clarity and for some pieces suited more.
It is difficult to generalise about pianos and tone, they are all so different.