Just try gpodder on your N900 with a moderately big datbase (say 100-200 podcasts). When you start a download, the 8 megabits coming from 3g to MyDocs, the 4k random write/read swap activity by the 8mbit io pressure making linux swapout to increase cache, and the random read/write to ext3 to update databases results in half-minute long stalls..

My home server also runs on flash. With ext3, the squid proxy server stalls for half a minute at a time when the flash slows down. With nilfs2, which by accident is quite performance optimized for flash, there are no stalls and doing a backup of the squid cache dir is also about 8 times faster than with ext3.