I tend to eat very little before my daily training runs, and i never fuel during them, Even my 'long' runs as part of a marathon buildup have often been done fasted and without fueling. However as ive switched focus to Ultra's ive started including what i call a 'time on feet' run every couple of weeks where the aim of the exercise is simply to spend as much time on my feet as possible. Then i dont worry about pace, or even distance covered, its all about being out for X hours, I pack a picnic lunch or two, and snack along the way...
I havent yet got to the point where i cannot or dont want to eat what i have with me, if or when i do i will almost certainly take to experimenting in training....
The old adage practice everything in training first still holds.