Not only NFS

SSD slow at write? Single X25-E can write at 170 MB/s, and Micron RealSSD tops at 250MB/s. Show me traditional disk capable of this. And it's general purpose SSD! I don't know how fast could be write-optimized flash used in hybrid storage NASes, like Sun Storage 7000 line.

There are some awesome benchmark numbers coming from system running ZFS with (~) external log and second level cache. They are coming mostly from extreme number IOPS delivered by flash, but interesting anyway. Just search for L2ARC and slog (separate intent log) results.