It should be doable with fast SD cards too and without a discrete save SRAM. If only the CIC were cracked you'd be looking at a relatively small ASIC, SD slot and oscillator. The only thing you'd have to worry about are games abusing cart SRAM which isn't likely an issue, and of course fragmented files.
I hope Neoflash adds support for the Neo2-SD adapter, then it will become interesting because you could put all your games on a single cart.
I'd much rather see a non-NeoFlash, cheaper and better product. I do agree it's enticing to be able to have your huge collection of "backup" N64 games on one CF card ready to go at a moment's notice.
I already have that with my Z64, though it is big, ok, but the heck, the n64 is not a portable anyway :icon_bigg
