I caught a glimpse of my doctor's notes (I'm pre-op) and they said something would be 300cm, and the common channel would be 200cm. I have a 46.6 BMI, so not 50+, but not mild obesity either.
He also said he would make the common channel longer (200) because it's less malabsorption, and because I could expect less gastro issues. I'd expressed some worry about the social consequences of being gassy and smelly, so maybe that's why. Or maybe it's the new norm for DS. Or maybe it's because SADI isn't covered by my insurance, so I have to do classic DS... but milder. Not sure