Just had the same whisky (Tullibardine 500 sherry cask finish) in 2 glasses: Spiegelau Authentis Digestive, and their Whisky Snifter Premium. Conclusions: the Authentis brings out a lot of sweet notes very quickly but presents a more "whole" aroma; the snifter, at the cost of emphasising the alcohol a tiny bit, seems far more analytical and showed a slight nuttiness which the Authentis didn't.
Which makes me think I'll be turning to the Authentis for white spirits — it would be interesting for grappa, in particular — but the snifter for anything where the slightly increased perception of alcohol is a price worth paying for the much more detailed aromas.
It's a strange thing to do, evaluating glasses in the hour before going to bed. But relaxing. Nosing whisky like that is certainly an exercise in controlled breathing…