Asked my dentist today about brushing right after eating, if it weakens the teeth (as declared previously in this thread). He said it depends what you ate. If it's acid food (e.g. orange juice, grapefruit), then yes, you should wait 1/2 to 1 hour before brushing. The acid leaches minerals out of the enamel and an organic matrix forms within the enamel that has to remain there for that up-to-an-hour period to replenish the mineral content of the enamel. If you brush before that happens there's nothing there to replenish the enamel and it's therefore weakened!
I also asked him about Glide and he says he dislikes it because of how slick/smooth it feels. He prefers a floss that is strandy, which is better at grabbing and removing plaque.