The new split idea is stupid, but a split between spirits and beer/wine would sort out the problems. The major problems have followed the raise in popularity of easy drinking spirits in the form of RTDs.
Raising the drinking age WILL make it more difficult for 14-17yr olds to get alcohol. (far less older school mates to buy it for 16 yr olds) This will reduce some of the harm immediately and overtime will help change attitudes of high school drinkers. Seems like a good idea 18 year olds can wait a couple more years, it certainly won't do them any harm.