What we did . . . and it worked great.
Made all of our ADRs for 15 minutes after opening of the restuarant (except Cape May, which we made for 30 minutes after opening).
Then we showed up 10-15 minutes before the restaurant opened. We were seated with the first group every time (including Cape May).
It was a win-win because we had all the benefits of having the earliest ADR without having the pressure of having to be there before the restaurant opened (we were relying exclusively on the buses to get us to every breakfast and wanted to build in some wiggle room).
Eating at opening has several advantages:
(1) You're likely to be seated very close to (if not earlier - see above) than your ADR time (instead of having to wait way past your ADR time).
(2) You hit the buffet when it is fresh and less busy/crowded.
(3) You don't have to worry about just barely missing characters (and having to wait forever for them to come around again). You get your food, sit down, and get the characters on their first wave.
(4) You can still hit the rides right at park opening (at least if the park isn't opening until 9). In fact, you might have an advantage over those at the front of the turnstyle if your breakfast location is closer than the turnstyle to where your first ride is. And even if the park opens at 8 (or has morning EMH), with an 8:15 ADR, you can get a FP before breakfast (one person gets the FPs while another checks in at breakfast).