I've put my souls into over a week worth of infinite stamina. I've replaced all but one piece of equipment with Tier 15 Legendary items (and one Tier 16 I got in a lot of 12), and sold off three different Tier 15 Legendary swords. Not one piece of inferno equipment has dropped. I've tried grinding up to Inferno 5-3 in the hopes that, while the rate of Tier 15 items is unaffected, just maybe Tier 16 items are more likely tO drop at higher stages. Edit: I just checked the rankings, and I've managed to grind my way up to 6th place on EXP leaderboard. Good grief.