Only trouble is if you have fish that would eat each other. I don't think it would be a very good idea for me to leave my 4 piranhas for 2 weeks without food unless I only wanted to have 2 when I got back.
I let the neighbor's kid take care of my tank. I individually package daily foods and have them color coded with stickers. Then he just comes once a day and dumps the entire contents of a baggy into the tank. I feed lighter when I am on vacation so there is less poo.
I like that idea! That way if you have someone who knows no idea how much to feed your fish its easier for them and you won't comeback to a real cloudy tank...or worse!