The STI gear cable interferes with most decent bar bags and limits the positioning of the levers.
9 speed generally sucks for touring, it requires to much care and feeding, it is always going out of whack. The front mech trim feature is very hard to use.
The affordable large ratio cassettes (11-34) have a lot of flex in the 34 ring so setting the end stop of the rear mech is tricky. The expensive XTR cassettes are stiff enough to work well.
I've ridden several multi-week trips the longest being 3650 miles all with 9speed STI shifters and have never had a problem. My wife's bike is set up the same way. So between us there is about about 12,000 miles of loaded touring since we switched to 9 spd's without a problem. We both use Ortlieb bar bags, and they fit just fine. The levers are exactly where I want them, and there is a lot of room for adjustment. It is what you are familiar with and personal preference. I built both of our bikes, and know how they go together. It took a lot of research and trial and error over the years to come up with a group of components that work well together. We've used the same drive train on 4 bikes with very good results.