For my concern it must be 272 MB with 128 MB on the CSPPC, 128 MB on the DKB 3128 and 16 MB on the Amiga 4000 motherboard.
Using a Mediator busboard it would be possible to install 6 x DKB 3128 and 128 MB on the accelerator, or even better 6 x FastLane Z3 with 256 MB on each board, if those 32 MB 30 pins modules ever got released. That makes it 1680 MB fast ram, but most likely the Amiga will not be able to handle this anyway :-)
My BlizzardPPC board is maxed out with 256 MB ram as well.