The PS3 is better in some aspects and worst in others. But's it's definitively less powerful in general (mostly due to the old GPU). See Skyrim for example.
Try copying some files with a PC and see if the same happens. I had the same problem with my SD, some blocks went bad for no reason so I had to RMA it.
Good job dude! Are your by any chance Brazilian? Also, where I can get that PornHub .cia? Lol, I know it's just a rickroll video but I can't find it anywhere.
IRC the bigger the cluster the better is the performance, but your files will take more disk space, since small files with the size under 64kb will take exactly 64kb.