Ok...here's my take on this.....no flaming please, this is just my opinion and what I consider vintage or not.
Post 1980 anythin: USED
1975-1980: used bordering on classic
1960-1975: Quality made American and Import drums-Premier, Sonor, etc(excludes the MIJ/stencil junk)--classic
1930-1959: Vintage-includes Premier, Sonor, etc.
1930-prior: Antique
Why did I pick 1930 as the change from antique to vintage? 1930 is around the time of the development of the modern drumkit as we know it...the modern Jazz era if you will....Gene Krupa, etc. Before that they were just traps sets.....and truly not able to be used on a regular basis today.....they are just to historically valuable and fragile to be honest. But thats my take on this subject.
Why did I pick 1960 as the change from vintage to classic? Gretsch changed to 6-ply shells by then, Leedy was owned by Slingerland and sounded nothing like they used to by then (ya I know it was 1955, but I'm generalizing all the companies here) Even the Radio Kings shell type had changed...some may say for the better, me I'm not so sure. This is pretty much the timeframe of the modern kit. You can play one of these kits today daily without much worry of breakage, yet it has that warm vintage vibe.
By 1975 the hardware was much heavier and the shells were thicker and most of the american companies were winding down and soon to disappear. Anything with a thick shell sounds modern to my ears so this is why I state borderine classic. Its a grey area for sure.
1980-onward is the modern era and the stuff is just used. My 1989 Ludwig classic maple kit, powertom sizes and all, was expensive then, (around $3500) but now its worth a fraction of that, even though its kept very nice and sounds good to my ears.....I know this and know that it will always just be a used set and never worth anywhere near what I paid for it back then.