fly rims are fucking awesome! ive been running mine for near a year now, they were built well and have lasted, to the extent that im only getting my first service done on them now.
My friend is running the front rim, and it is by no means weak it is very strong and will take the abuse of many people. it is meerly lighter due to more holes on the top layer. Dylan smith and many other fly riders have been using the front rim on the back and they have lasted amazingly from what i hear.
id suggest getting the front, it will be lighter and ultimatley help the feel of the bike