hiya,
well i have been told both
my gp and hv told me avoid soy oil and soy lecithin but my dietician and paed said it was very unlikely that he would react to them (he has multiple food intolerances which includes soy) as even LOs with soy allergies are often fine on these. reason being as you said, the oil and lecithin are so highly refined that the protein is very broken down. (how's that for confusing!)
i did avoid it for the first two months of the ED tho as wanted to get him stable before messing with anything.
interesting that you have soy oil in neocate as it's not listed on my LOs neocate??? i'm in australia, where abouts are you?