I had 2 STI levers in my touring/commuting/everything bike ;-)
We had a 4 month tour with no problems.
When we returned I tried to make adjustments to the front dérailleur, and broke the front STI lever.
I had 2 barcons from my wife's bike, so I mounted one on my bars at the left for shifting the front dérailleur.
This was a quick fix.
So now I can tell you about the difference ;-)
I really find the STI far better then the barcons. It's easy, it's up there, and I don't even use the STI brakes as I use the cross levers.
So to do some shifting I need to move my hands to the shifters. I find the STI much more stable and easy. The barcons did cause me some wobbles when shifting.
If I would ride most of my rides with my hands on the bottom of the bars near the barcons, then I think it will be easy to operate.
I do prefer STI, as I like to ride on the top and on the hoods.