As far as I remember, there were comparison tests for NAND and eMMC speed, and NAND is *much* faster. Can't link to results now, though. Also, keep in mind, that more crucial things on eMMC, more I/O conflicts between it and regular read/writes. We have already avoided it by using swap on microSD, so introducing it back again, by putting things from NAND into eMMC doesn't seems like good design decision at all.

By the way, I wonder, why You have problems with space on rootfs. Currently, I got 55 MB free, *without* deleting any locales, moving any things to eMMC etc. I think You got something eating Your rootfs space (.cap and .ivs files from aircrack? Not optified packages?), cause during normal circumstances, it should not result in "out of space" in any point of time.

Of course it's up to You, and experiments may be worth trying just for sake of knowledge, but it seems for me that You're cutting of leg, instead of curing it.

/Estel