Originally Posted by Heron Todd
The other problem with brifters is how they can limit your gearing choices. Shimano brifters cannot be used with MTB-type front derailleurs since the required cable pull is different. This means you are limited to road-type front derailleurs. These don't shift well over smaller chainrings with an indexed shifter. They will work OK with a friction shifter. Loaded tourers will generally use smaller chainrings, hence the problem.
It's not really a problem. I'm using a set of RaceFace Turbines (46/34/22) on my touring bike with a Tiagra front that shifts just fine with STI shifters. I'm also using a Shimano XT trekking crank in a 48/36/26 with an Ultegra on my commuter. They work too, however the Ultegra isn't as good a triple front derailer as the Tiagra. It's narrower in between the plates and is touchier about set up.