It probably depends of a lot of things. How much will you carry? Are riding in each day and hiking? What season? Etc. I used the 3200 last fall as a day pack off a horse but I was also carrying my gear (lunch, water, puffy, rain gear, map, GPS) plus gear for another. I also try to consider the horse and the fact that they gotta carry your stuff as well.
Not sure if that helps but I think there's a lot of questions yet to be answered about your specific needs.