Never mess around with a new food on race day. That's even more important than clothing.Try it out on a training run and see how it goes. Some people's stomachs just don't agree with them, or with certain brands, so don't mess around with ruining your special race day!
Here's a little link about it that I think sums up the pros & cons decently.
http://www.allaboutrunning.net/sri-chinmoy-racesblog/energy-gels
Personally, I drink at every water stop, but never take any food/gel of any kind in before 7 miles, but I've also heard that you should take them earlier because your digestion process slows or stops later in the race if you're really under duress. I would imagine everyone is different and there's probably lot of different theories out there.
Always, always, always take them with water...and not with sports drinks or just alone.
I never figured out the thing with jelly beans. Wouldn't candy set you up for that energy loss feeling? They're not made of the carbs that easily break down. Maybe people use them more for a psychological treat to say "good job, Me!" ??
Does anyone know what brand of power gel is offered on the Princess course? Usually I tried to match my training with what was offered in a marathon in case I needed something and ran out.