If it is a meal you really want to do, then I would say it is worth a $20 cab back to Pop so you don't have to worry about Disney transport. I really like that breakfast. If you can afford the cab fare. Sometimes we (and I am guilty of this too) fret over spending 20 for cab when we've spent thousands to have a magical trip.
Im not suggesting you be late for the Magical Express, I personally wouldn't, but last time we left, our driver said we were supposed to have like 50 people on the bus, and we had 6, so I'm confused how the other people got back. Did they all take cabs, or did they accomodate them on the next bus. (if capacity was available). Like I said, I'm not suggesting that, it's just something I've wondered about.