Doing endurance race pace rides you'll burn 600-800 calories/hour. Anyone that can eat and process more than 300 calories/hour, wow! That's awesome. I've seen this before in person (Rocky Gingg was eating Freebird burritos on the bike and fistfuls of M&M Trail mix), but wondered even if you can handle it, if you're not pulling too much blood flow away from your muscles to digest all those calories?
The reality is that we have a few hundred calories worth of glycogen stored in our muscles, after that's gone, we (most of us) can process about 250-300 calories per hour of fast absorbing sugars (4% glucose, 4% Maltodextrin usually in sports drinks), the rest is going to come from fat if we're going slowly enough, or muscle breakdown if we're pushing things.
You can go fast or you can skimp on nutrition. I don't think you can do both.
I highly recommend the book "What Comes First, Cardio or Weights?" by Alex Hutchinson if you're interested in any of this stuff.
And yeah, I second everyone saying "do what works for you and don't experiment on the ride with what you haven't tried in your normal rides".
For me, I have done 24 bottles of Inifinit for a 24 hour race without any real food and feeling pretty good. Sometimes on long rides though, one of those gas station cheese peanut butter cracker packs and a coke (+water) will sub for one of my bottles and helps a bit mentally. For 90 minute rides or less I can do water, but in the summer I can get behind very quickly on electrolytes, so at the very least I throw in some Lite Salt (50% KCl 50% NaCl) into the bottle, but I usually drink Infinit in the summer even for short rides. I have too many side-effects of going without electrolytes otherwise.