The other difference between Oban and some of the Islay peated malts is that Oban sources their peat from the Highlands and most of the Islay malts source their peat from Islay itself. Typically, Islay peat has more of the medicinal/iodine profile and the Highland peat more of the bonfire smoke, earthier.
Port Charlotte, that
@Irish recommended (great call btw, Matt!), sources their peat from the Highlands as well, so one can see the difference in profile between the PCs and some of the other Islays.
Diageo, who owns the Port Ellen malting facilities, announced that only their own distilleries will be allowed to use their peated malt. It will be interesting to see what will happen with some of the distilleries who will have to source their peat elsewhere. My guess is it's just a negotiating tactic and nothing will change, but the price.