I'm so sorry for the late reply, I rarely look at the boards and you are right- lots of bullies! We haven't had a problem with formula but one of the brands made her spit up slightly more than usual. We like the one from Wholefoods called Babies Only best. The only differences we noticed is that she does prefer the taste of breastmilk so sometimes she doesn't want to drink the formula (usually if we try again in five minutes she will). The other difference is that it definitely keeps her fuller longer which is nice at night time!So long as you are still mostly breastfeeding they are still getting all of the antibodies etc. so there is no disadvantage to a few ounces of formula here and there especially if you pump to maintain your supply. It is much worse for them to be short on the calories that they need to grow AND for their mom to be stressed out. Whatever you decide know that it is the best decision for your family because you are the one who made it! No one else knows better than you even though they sound confident from behind their computer screen.