Many people die each year from NSAID use, I think because of the gastrointestinal damage it causes. Many prescription NSAIDs are said to be more effective than the over the counter types-- like tylenol (acitominophen) or the very dangerous (reputation) ibuprofen-- and these prescription NSAIDS are often designed to be less dangerous to the body than the others, and so safer for long term use: vioxx and celebrex are the ones represented most often by people here. They also are reproted to be more effective. Daypro, however, is not designed to be especially safe on the body.
take care, and congratulations on finding things that work for you already!