SCOTCH-WHISKEY>>>How much better is Buchanan's 18 over Buchanan's 12?

Now, i'm really not much of a scotch guy but I did try Buchanan's 12 a few months back, and wow, that was some good stuff. Worth every penny and every drop. It was very smooth and tasted great, so great that the question popped into my head; If Buchanan's 12 is this good, is it possible that Buchanan's 18 would be that much better, enough for their to be a 100% price increase? I bought the Buchanan's 12 for $25 on sale and I have seen Buchanan's 18 an sale for $50. Is it truly worth it?