The 2 things you are going to have to take into account if you choose to run drain to waste are...
#1. Are your plants getting enough nutrient in their feeding to justify wasting the remaining nutrients?
#2. Do you make/get your nutrients very cheap and be able to waste the excess nutrients?
The plus side is that the there will be little to no salt buildup.
The negative side will be the price of the nutrients pending how much you use ie. method and number of plants.
True Aeroponic Growing (TAG) is probably the only real method where drain to waste is going to be optimal.
Cheers Jimmy.