Rabbit/gate starts are great for practice for 5-20 boats but after that they get a bit sketchy.
The Buzzards Bay Regatta uses them every year for 505's and Vanguard 15s... i've done it with 80+ Vanguard 15s and there are some hairy close encounters with the rabbit, early/late duckers, and etc.
This wouldn't work very well in catamarans... for one it requires reaching to go sail under the rabbit and then heading up.... this would be way to fast and dangerous in close quarters with other boats. In addition, people do purposely avoid being the rabbit as it is usually a slight disadvantage (can also be an advantage) ... at BBR it is the 7th place boat from the previous race that becomes the rabbit and often you will see people give up 7th place right before the finish to avoid being the rabbit.
I've also seen the rabbit hit many times in slower, more maneuverable monohulls.
It is the fairest way to start but it takes away the importance of having the skill of knowing how to do a traditional start.