Is there any reason NOT to switch to follow on formula?

[2point4kids]

DS is 7.5 months and on Aptamil.
I am thinking of switching him to follow on milk as he eats well and has a good variety of food.
I know that you dont need to use follow on milk, you can keep using the first milk until they go onto cows milk, but follow on milk is cheaper so I want to swap him onto it unless there is any reason why I shouldnt.

Is there any reason why I shouldnt change to follow on milk?

I've heard that follow on milk is a con, the companies make it just so that they have a product they are allowed to advertise! And apperently it contains more iron than a baby can absorb so instead it can cause constipation. But try it I guess and if your baby is ok, why not if it's cheaper!

it is not necessarily a con.. but as first milks can;t be advertised or promoted, it is something that can be

i would switch purely for hte money saving

you can use cows milk in cooking now , but not as a main drink until 1