We also saw more gas in Prilosec (we used the compound) and saw it reduced when we moved to Prevacid (although the Prevacid never really kicked in for us).
The Prilosec worked better for our daughter’s reflux. The GI moved us to Zegerid today, which has Mylanta mixed with it and gave us something to relax her for the gas. She also said to make sure the baby poops every day (use a glycerin suppository if necessary) to ward off these crazy night “gas fits” our daughter has been having.