So for a 20 ft boat, you'd get a 60 ft zone around each mark...thus 120 ft minimum between the marks. I've certainly sailed races where the whole gate is only about 3 BL's long.

I guess I'm more concerned about what happens if our STRB boat is coming in near the midpoint of the gate, PORT boat(s) can't know for sure which way he's going to go through the gate. If he wants to go left (looking down course), they need to make room for his gybe; if he wants to go right, they need to make room for his harden up. Until it becomes clear which, the port boats will have a hard time planning ahead.
This is no different for the '08 rules...just things get more complex trying to discern if strb goes out of a zone thus lossing rights to port boats....can't strb just claim to be going to the other mark and still have rights??