As I understand it, the Fine Oak range is a vatting of both sherry casks and bourbon casks, (i.e. not exclusively one or the other).
I've tried three different single cask Macallans that were ex-bourbon, and whilst they were good, drinkable whiskies, they didn't blow my socks off.
These days, a great Macallan is identified by its sherried richness, sweet fruits, and good balance. To change the formula by vatting in bourbon casks, they can't honestly expect a knowledgeable market to get excited about it!?
It strikes me as an exercise in cutting costs, and increasing profits: Bourbon casks are considerably cheaper than sherry casks, so - in theory, with all other things being equal - the Fine Oak range should actually be CHEAPER than the regular bottlings.
If Macallan want to return to their hey-day, just start sourcing some good sherry casks again, go back to using Golden Promise barley only, and then see the market start to sing their praises again!