My understanding/take:
DuoDock:
- The only one with Snow White grooves on the top lid, pretty...
- Top lid height means it will only accommodate B&W Duo's: 210/230/250/280
DuoDock (with new taller, flat lid):
- Apple definitely sold a lid upgrade to accommodate color Duo's in the original DuoDock: Adds support for all Duo's (+270c/280c/2300c)
- I think (but not 100% sure) Apple sold this config as the DuoDock after the DuoDock II was released
DuoDock II:
- Supports all Duo's
- New taller lid with smooth flat top
- Slightly redesigned case with improved cooling vents
- New Logic board:
-- Built-in AAUI Ethernet
-- Built-in 1MB VRAM (Original DuoDock had 512KB soldered and an expansion SIMM to add 512KB)
-- Upgraded onboard video (slightly faster, more/higher resolutions, compatible with SVGA, etc.)
-- Built-in 68882 FPU (ONLY works with 68030 Duo's, original DuoDock had socket for one)
-- Built-in 32KB L2 Cache (ONLY works with 68030 Duo's)
DuoDock Plus:
- Supports all Duo's
- The same as the DuoDock II but new logic board removes:
-- No Built-in Built-in 68882 FPU (also no socket for one)
-- No Built-in 32KB L2 Cache
The DuoDock II is the "best" from a feature standpoint, especially if you have a 68030 Duo, if you don't then the DuoDock Plus is just as good. In both those models you have 2 NUBUS slots to do other things with. If you put decent NUBUS Video and Ethernet cards in the original DuoDock w/lid upgrade it can match a II or Plus but you've used up your slots (kinda what they're for though...).
