I listened to the Gershwin and Rachmaninov preludes. Impressive playing but rather too ragged in places. I did not like the sudden tempo rushes in the Rach 3.2. The Rach 23.5 is well done (apart from all this mistakes

but could do with some more long-line phrasing and rubato. The double-octave runs are too slow compared to the rest. But quite a feat to take this prelude up at the required tempo ! A shame that the acoustic seems to blur much of the detail.
Sheesh, 8 pianos. I always find the sound of more than 2 pianos unbearably cacaphonic and messy. But it must be great fun to do !