Survival over what period and usage pattern? Keep in mind that flash writes impact the entire block device (not partition), so having things like swap, journal, .ash_history etc on the same chip have a cumulative wear effect.
BTW, there was some speculation that there's an extra (faster?) memory device in the RX-51 specifically for swap use, but I've lost track - was that ever confirmed either way? If there is, it could also be used to store the ext3 journal.