Nutritionally I can't fathom how GMO food would be a problem unless it contained things that were "not naturally found" on this earth. Our bodies (and the planet's flaura and fauna) evolved in the presence of the elements that are already here so "splicing" them together still is using the same elements and our bodies should recognize them and know how to deal with them (as should nature).
It's true that I am a bit skeptical of dietary ingredients that are out of balance with each other or not in the presence of the co-ingredients that our bodies are used to seeing (ie: vitamin c from fruit vs vitamin c made in a factory) but from a scientific point of view vitamin c is vitamin c so there really isn't an argument. To me though, somehow it seems right that my body would recognize the fruit and absorb the vitamin c alongside the other bits of the fruit more efficiently than vitamin c in a capsule ingested without the presence of the other bits of the fruit. Maybe just emotion though...
The reason I said I don't like monstanto is simply that I worry about losing biodiversity if the man made plants or animals get loose. I worry that the evolutionary balance may be negatively impacted if the man made things get loose (example: such as farmed salmon that don't know how to migrate and breed).
All said, managing the science is more the challenge for us silly humans because of our greed and emotional responses to things. Banning the science makes no sense unless we wan't to go back to 50 year average lifespans. It's like a gun, gun's are OK as long as they are used properly.
(had to get firearms into this you know...)
'nuff said.