You definitely don't need to rinse the bottles when they come out of the Milton. I guess some might want to rinse them as Milton does have a smell to it, but it's perfectly safe for babies. The smell is worse when you open the lid, just because it's been enclosed!
We had awful nights with the powder formula as we tried making it up quicker than suggested on the tin and then it goes all lumpy - there was one incident (known as "the night of a thousand teats"), in which we got through ALL the teats in the Milton as they kept getting blocked!!! Cartons are not cheap, but when you have a screaming baby they are worth their weight in gold! We didn't use them because our LO was on special formula (GP was reluctant to prescribe cartons) and it would have meant giving her different formula at night.
We had awful nights with the powder formula as we tried making it up quicker than suggested on the tin and then it goes all lumpy - there was one incident (known as "the night of a thousand teats"), in which we got through ALL the teats in the Milton as they kept getting blocked!!! Cartons are not cheap, but when you have a screaming baby they are worth their weight in gold! We didn't use them because our LO was on special formula (GP was reluctant to prescribe cartons) and it would have meant giving her different formula at night.