I agree with Bumbershoot; if you're up early enough to take advantage of MM, you won't want to waste it eating. That's prime time for walking right onto rides that will have hourlong waits later in the day.
I like how Ridemax tips section puts it: "Breakfast? What breakfast?!"
"Regarding breakfast, since arriving early in the morning is such a key to beating the crowds, our preference is to grab a quick bite to eat at the hotel, rather than waiting to eat at the park. Later in the morning we can then take our time eating an early and leisurely lunch, when the park is more crowded and the timing for riding attractions isn't so critical.
"If you do decide to eat breakfast in the park, be forewarned: you could face a substantial wait just to order your meal. Consider the picture below, taken during the holiday season on a Saturday morning at 9:20AM. Do you see the line which begins in the lower-right-hand corner of the picture? That isn't the line for Pirates of the Caribbean, it's the line to eat breakfast at the River Belle Terrace restaurant, which we estimate was already 40 minutes long!
"Despite our warnings to the contrary, should you find yourself wishing to eat breakfast in the park, the lines in the Tomorrowland Terrace area should be shorter than those shown above, and during less-busy seasons of the year the breakfast lines also won't be as bad. Just be aware that even if your wait is minimal, eating breakfast in the park will still use up a good chunk of your valuable early morning time, when the lines for the attractions are at their shortest. "
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On a side note, we like to keep breakfast items in our hotel room; grabbing fruit, granola bars, milk, juice, poptarts, etc. and sometimes eating them while standing in line at the gates for MM. Have just enough to tide you over. Then you can make PS reservations for a late breakfast/brunch at 10:30 or 11 a.m. at Carnation Cafe or Plaza Inn, or something like that.