AIWB isn't more comfortable for me, I do it if I need better concealment and it's not bad if I'm standing or walking. That said I'm more comfortable with a more traditional 4:00-4:30 IWB. My back isn't good, I go to a chiropractor once a month if everything's working well. If my back is bad, I pocket carry a g42. I guess it depends on the location and severity of your back pain. When my back is hurting (lower back) , AIWB is not an answer for comfortable carry. But in all fairness I only carry appendix about 20% of the time and don't find it especially comfortable under any condition, but everyone's different.