Same as comparisons of class 10 vs class 4 SD cards. Random readwrites make all the differnce for something like booting ubuntu. For HD recording none. In different tests you will get different answers. Try reads from rootfs of highly compressed data like binaries/.o's. Totally different results when writing 1010101... sequentially, all kind of algorithms kick in in between your test and actual write(/read). Best method to check is just starting microb as Nokia made it (rootfs) while clocking and/or camcording time. Restart, move to opt, symlink, restart, clock it and camcord it again and compare. No place for placebo bias.