Originally Posted by
TANC
Yes, the internal cable hype has me a little pissed, too. Better protects cables in weather, more aerodynamic, but doesn't work as well. They leave out that last part. Never had a seconds problem with my Allez and 105 stuff. I wanted the electronic version, but was told not to. Said out of the few they had sold, several already had problems. "Buy the mechanical version and never have problems." Yep.
Other than possibly being a PIA when replacement time comes around, there's isn't any drawback to internal cable routing if it's done right. Two of my bikes have it, and both shift smooth as silk.
The OPs shifting problems seem to have arisen from a specific bad cable routing, which caused some binding. That shouldn't be used as a springboard to indict internal cables in general, nor for a particular groupset.
IME, cable friction, whether from poor routing, liner wear, dried lube, or ferrule issues, is the number one cause of problem shifting. It plays no favorites, affecting the full range of systems from all 3 makers, and can make any derailleur shift like an entry level off brand, set up by the worst mechanic Walmart has to offer.
One key to being a decent mechanic is to recognize cable friction by it's effects, and address it promptly and properly.