Rum detracts from the peat notes. I miss the old Longrows from 2013 and earlier with more peat. I think there must have been larger casks being used and less sweet wood (sherry, rum etc). Either that, or the distillery used to have a slightly higher phenolic content. Not sure which. Take me back to the good old days. I want more peat in my 18's once more. This said, the rum needn't detract. In this case, the wood was just too saturated or perhaps it was the type of rum wood used.
Can you imagine a Springbank or Longrow aged in a Bellevue cask? I'm not opposed to rum. I have plenty in my collection still but they are "scotch lovers" rums, such as the dark, complex kill devils.
If it must use the rum wood, then I think Springbank (for the Longrow 18) might splurge with some more interesting rum casks, such as what Glen Scotia used recently for its festival release. Finishing for a year would do that, rather than sitting so long in the sweet wood. But I know that finishing is not done so much for the 18. Rather, it's sweet casks vatted with the other refills and bourbons.
Ah well. It's only an OB, after all. For 18 OB's the Longrows are far better than most distillery releases, aside from a very few years when the sulfur is overpowering, which is rare. I like the previous 2017 release a bit better, aside from that one off note cask with a case of "sulfuritis."
Without the slight sulfur influence, the 2017 Longrow OB would have been really really strong. I almost never like sulfur. I feel it is a flaw and not a strength no matter how much is marketed to the contrary. I can't think of any distilleries that leave sulfuring agents in the wood for the purpose of imparting that scent/flavor. We should call a spade for a spade.