I'd say #2's about right, with the caveat that it's all based off avg adult sized hands. I'd also add a 4th for micro/pocket sizes
Full: Duty weapon, not ment for concealment
Mid: Slightly smaller, somewhat easier to conceal with minimal usability sacrifice
Sub: Small, often 2 fingered w/out pinky ext. Easy to conceal, harder to shoot well at a distance
Micro/Pocket: Tiny, cake to conceal, often hard to shoot well past "get off me" distance
ETA
Monster: Full size+, de50, sw500 etc etc. Larger than normal "full sized"