I'd say about 80-85% keep it long. Practice putting it up in a neat bun (fast) and you'll be go to for both Beast and the school year. Yes, it gets annoying to have it up a lot, but you can make it more feminine with braids and a headband the color of your hair. Post earring help. Also, there are a ton of situations when you can let your hair out of a bun: in the barracks you can put it in a ponytail; corps/club squadders can wear a ponytail to, from, and at practice; during Spirit Dinner (every thursday) you can style it however you want including putting it down and straightening it or whatever you want; retreats and dance classes and trip sections many times allow you to wear civies so you can have your hair however you want. Also, as you move up in class year, the standards relax and you can wear your hair down or however you want more and more. It would be annoying to cut it so short for all of plebe year and then have to grow it out for the other 3 years. Just keep it long, trust me!!!!!!!!
The only exception would be if you really like having short hair for some reason, in which case the people who like styling their hair short don't have any problems doing it.