Samples in arranger rom-memory (32-64-128 megabytes) are no match for hard disk streaming samples (multiple gigabytes). That's just a plain fact.

The piano piece I mentioned was 'thrown' togehter by a good pianist, just using the Post Bosendorfer 290 Gigasamples(http://www.postaudiomedia.com/producthtml/bosendorfer.html, $199)

Like Frank I'm seeking to combine the best of sounds (= disk-streaming, certainly for acustic instruments) with (software) arrangers.

There is still a way to go, however.
For instance: so far there are no satisfactory 'streaming' GM sets which can be combined with (software) arrangers.
I do appreciate the great amount of tweaking done by arranger engineers. However, the sample technology used (rom-sounds) is not the best, simply because the "no-loop", "nach note sampled 8 to 16 times" (velocity layers), requires gigabytes.