As far as I know, the Flash or SRAM cards do not give more "RAM" to the
Zoomer, but they give more "DISK" space (ie space for your saved documents)
This Disk space may be compressed via Stacker (embedded in the cards) or
other compression utilities. In my opinion, compression would not be
very efficient (not fast enough) in the Zoomer (to be confirmed).
In any case, this kind of memory is sufficient even to improve the Kernel
behaviour because GEOS does virtual memory allocation ans swaps memory
to the disk when it needs some free memory. This slows a bit the Desktop
GEOS (f it swaps on a hard disk) but should not be noticeable on the Zoomer
because the disks are made of silicium.
Well, these are rapid statements, the things are more complicated, but it
gives a idea.