I honestly don't think it really matters if they don't get fed at all when you are leaving for only a few days. An auto feeder is good, but I will NEVER allow someone to take care of my fish for me again unless they are an experienced reefer too. Everytime someone fed my fish I came home to algae blooms and sometimes dead fish.
I tried out making little daily portions for them to feed each day. When I came back there was the usual algae bloom and unhealthy fish. I aked them "what happened?" and they said there wasn't enough food in the portions to keep the fish well fed and so they went out and bought goldfish flakes. Never again will I let someone inexperienced take care of my reef. Now to get back on topic.
Most healthy fish can go without food for weeks so a few days is nothing. Getting fed a little is better than nothing and I would keep feeding like normal up until the day you leave.
