I've been using STI this season, but I'm leaning towards bar ends on the new ride.
I've only had some minor reliability issues with Ultegra STI - a few times this past year my rear lever got stuck and wouldn't downshift - so I was stuck in a low gear. Took some screwing around with the R.Der (nothing jammed, etc) and the lever. I eventually grabbed the cable under the downtube and yanked on it. Whatever was stuck inside the lever let go... and it popped back. Its happened a few times - but I wouldn't call it a deal breaker.
The new ride will probably have bar ends, as I'm interested in trying out various handlebar combos - I may switch out to STI after I get my fit / preferences down - but at this point I'm probably stealing parts off another bike (my touring rig) as I decide what I like / don't on the new rig.
STI is convenient, and I do alot of standing climbing - so shifting while standing is nice.
I think the failure argument is OK on world tours, but on Brevets you are typically withing reach of civilization at most times... granted, if you have a failed STI you probably won't be able to shift until you get to a shop - with a bar end you could go to friction mode...
So long. Been nice knowing you BF.... to all the friends I've made here and in real life... its been great. But this place needs an enema.