One possible compromise between bar-end and STI might be the Kelly Take Offs:
http://www.kellybike.com/2nd_xtra_takeoff.html
I installed these on my Salsa Fargo recently and they seem to work very well. You can use the bar-end shifters you have, or upgrade (as I did) to some Dura Ace downtube shifters (they have a slightly longer and straighter shifter). I like this setup because it gets the shifter up closer to where my hands usually are on the bars. I find shifters on the bar ends always seem to end up being bumped by my knees at stops - which both shifts them into unexpected gears, and also irks my knees.
(Note: The pics below also show a second straight handlebar segment mounted on a second stem - that is simply for getting the handlebar bag a little lower and also freeing up more real estate on the top bar, and has nothing to do with the Takeoffs - though I did discover by accident that having the second bar there allows me to use it as a base for my hands sometimes when shifting from underneath the top bar - you might do this sometimes depending on the position of the gear levers).
Neil