neenztwins - you have put your finger on why this topic can produce such polarised opinions. What we see in our day-to-day lives is very often what you see - babies who were ff and who do not have major health problems. We also compare our own direct experience of our health to the stats.
But that's not really good enough! Research takes many thousands and thousands of babies, and among other things, counts their episodes of infection, hospital admission, rates of obesity, development of diabetes, incidence of cot death, and so on and on. It then finds out feeding experiences. It also finds out social and economic factors and number crunches the whole thing to ensure these social and economic factors are controlled for (so we are measuring feeding, not deprivation levels). This takes us way, way beyond anything that we can observe in daily life, I'm sure you can understand.
To give you another example: I know (fortunately) no one who was killed in a car crash because of not wearing a seat belt. In fact, I grew up in a family where no one bothered with car seats for us kids. My dh was the opposite - his mother was very conscious of safety issues like this. We have both survived, but we are both fanatic about in-car safety for our kids and other passengers. I have realised that my own experience and observation is pretty worthless when it comes to judging car safety - the statistics have convinced me, even if the law didn't. This does not mean I think ff is the same as not wearing a seat belt - I am using this example only to demo. the value of research and statistics.
If you want to read the evidence, then a good site to visit is www.babyfriendly.org.uk which has a good collection of referenced articles, so you can read for yourself the difference, not just to infant health but to maternal health, as well.