I use S26 AR, and I noticed a change in Christopher after his very first bottle of it. Within 24 hours it was like living with a completely different baby.
I use Avent bottles with multiflow teats, he has been having the number 3 (fastest flow) since he went on it at 2.5 months old.
Just one tip, I find that it is not great to pre-prepare the bottle as it goes lumpy after a little while. I just fill the bottles with boiling water and chuck em in the fridge. When he needs it I put the bottle with the water in the mic for 35secs and then add the formula.
Each baby is different and be prepared to try a few bottles, teats, formulas before you find the right one. Christopher has severe silent reflux and probably will till 18 months, and then may have to have surgery if it dosnt correct itself so he will be on the formula until he dosnt have a bottle anymore. But thats cool, as soon as I saw the difference in him I didnt mind. Hope this helps
Christopher 08/10/05 William 30/12/08