OBG wrote:What are the advantages and disadvantages flavour-wise to these variations?
To add modestly to the discussion...
A major advantage of higher proof and cask strength whiskies that have not
undergone chill filtration is the retention of long chain fatty acid esters (easily 'stripped' from a spirit that has been chill filtered), the presence of which positively affects textural depth and flavour profile. Islay whiskies that are
chill filtered appear to be especially prone to negative consequences aroma and flavour wise.
Of course, the ability to 'fine tune' a high proof or cask strength whisky as you see fit also plays into the equation positively.
That said, sometimes
, the fact that a whisky has been 'rendered' to a lower (more standard) level of alcoholic strength 'at source' is a plus, in that the water utilized by the distillery carries within it certain flavour characteristics, which complement the whisky.
The question of consistency (relating to the nature of the water one adds to one's high proof or cask strength pour) is, as has been pointed out, also a consideration.
For me, though, the benefits of higher proof and cask strength whiskies far outweigh the drawbacks.
Just don't fall into the trap of bringing every high proof or cask strength whisky you pour down to a 'standard' ABV level of 40 to 46%. If there's one thing experience has taught me, it's that many such whiskies 'fall apart' in the glass when treated this way. Far better to try such whiskies straight up to begin, then adding water a drop at a time until they seem to be 'working' for you as they should. You'll likely find that an alcoholic level from the high 40s through the mid 50s (or, perhaps, even higher) seems to offer the best combination of flavour intensity and degree of 'openess'.