Normal Luk Versus Lukless; When do they surpass?

Eh.
Lukless is always slightly better, and significantly cheaper for equivalent equips. (The reason why godly lukless stuff is so expensive is because, simply put, it's godly. If you don't bother with that kind of equipment, and just stick with decent to semi-decent items, you'll still be more or less on par with good luk/low luk mages and spend a lot less.)
But the difference isn't great enough to warrant resetting, really.