The only thing I've noticed about taking 6-7 am flights is that unless you are used to getting up at 3-4 am already, it throws your system off for a couple days. We used to do the real early flights for cruises. But after noticing that we were always just too tired to function that day when we arrived and weren't much better off the next day, we decided it was better to just fly in the night before and eat the extra night of hotel rooms. While its not the exact same as what you are doing, I would probably figure on an extra nap once you get there.