Ah, you beat me to it Lawrence
I've heard from others in this forum that some time ago Springbank expressions benefitted from the use of older whisky in their single malts.
Now, I haven't tasted any older Sprinbanks partly due to the rarity but also the price you have to pay for older 21yo etc.
However, the present 10yo 100 Proof is in my opinion a very good single malt and has a certain "sour" smoke character I have only detected in Port Ellens before. My speculation is that it could
have something to do with the "manual" peating process as opposed to the fully automatic/mechanised you see in Port Ellen Maltings today.
I feel it's a bit unfair to suggest that Sprinbank is a bad or not top notch single malt. True, it may not taste as it used to but it is objectively not worse than any other iconic single malt in the market. If your preferences include a big explosive mouthfeel then the 100 Proof will do nicely. And I'd say they're worth the money too.