My thoughts.
NAS - There seems to have been a change in the distillery being bottled. I know the reps won't say anything (I've asked) but my suspicion is that the stuff from 2000 era was Glenrothes and that about 2 or 3 years ago they switched to Glenfarclas. It is good quality for bargain basement single malt (under $20).
5 yo - I have a bottle but haven't tried it yet.
21 yo - Well it is a big step up from the NAS. It is priced very reasonably for a 21 yo at around $75-80. Really need to spend a little more time with this one.
100 proof - Well I just got the bottle. What do you want?

