I am not commenting the wiki, nor whether there's a need to reformat all partition in N900. It's okay if one wants to format any partition with any fs, as long as they're willingly to take the risk. I'm just commenting on the suitability of using ext4 fs on flash media. May be I should have stated it explicitly next time before posting.
Thank you for sharing the links. However, I found that neither of them include vfat in the benchmark, rather I found one here. Nevertheless, I'm not going to defend for vfat. I've no sentimental attachment toward vfat, I'm glad to know ext4 is better than vfat. For the performance, we can always do our own benchmark to convince ourself. There's no need to argue on that. Take it easy. ^^
Again I'm not talking about reformatting NAND, I'm just talking about ext4 on flash media. BTW, NAND in N900 is formatted in UBIFS, which does not work on top block device, but still it's a file-system anyway. UBI itself is a wear-leveling subsystem but I'm not referring to that in my point. Without wear-leveling, ext4 is not the best choice for flash media. Ext4 does not handle wear-leveling in its original design, but flash manufacturers consider including wear-leveling in hardware so the problem would be solved in the future. Just for your information.