I have never tried a Mortlach before and am itching to buy one from TWE in the near future. The two that have caught my eye are the G&M Mortlach 21YO and the Murray McDavid 18YO 1988/2006. The supposed casking for these bottles are sherry and bourbon respectively. My question is which type of cask would give the most "authentic" house style of Mortlach? I am only considering buying one bottle.