Back when they first came out they were stae of the art, tooth count wise (compared to 20 tooth ratchets). Since the 60 tooth ratchets and higher came out not as much but still hold thier own, especially against 36 tooth & under. To me the 60 tooth Gearwrench style 3/8 ratchet feels real close to the 3/8 drive S-K ratchets.
IIRC, the 1/4 is 60tooth, 3/8 is 50 tooth, 1/2 is 40 tooth, I dont remember on the 3/4 drive off hand. These are for the "Pro" ratchets, All the "Tuff 1" ratchets are 72 tooth.
As was said they're an older design (from late '30's), but they still make them for a reason, IE; little has changed about them, they are that good.
IMO, the 1/4 drive S-K 40970 is the best one available in regards to price, size, tooth count/swing arc (8*).