I think a good point to bring up is that when people are targeting the official client (with smart anyways) they're only playing 1 account with that machine (be it vps, vm, etc). Thus 1 cache per active bot (plus potentially other factors, ips, unique hardware, etc that we don't/unsure about jagex using to link/flag accounts).
So while there might be (I'm positive there would be) a lower ban rate via targeting the official client, that however doesn't mean that it being an official client or not is actually the main reason behind that statistic.
@
Flight what are your thoughts about that ^?