Yes S-26 has that reputation (for constipation) but it is such a popular brand that the majority of babies on it must cope fine. My MCHNs warned me off that brand for that reason but I know heaps of babies who have had it and have been absolutely fine.

I'm glad that you have worked it out and found a formula that works for you. It's so hit and miss...you look at the vast array of tins and you just have to pick one and hope for the best.