hey broken. i know you know what you're talking about, but you misspoke a bit.
overburning refers to putting more data on a disc than it technically can hold. this discussion is about overspeeding.
other than that, everything you said still applies.
some drives come with utilities to allow overspeeding (benQs for example) If your drive does not have a utility for this you'd have to edit the firmware.
unofficial firmware voids drive warranties.
there's no guarantee of burn quality.
unless you're using top of the line media, you're going to get unreadable crap as a result.