I have two bikes with internal cables. Its hit or miss. Sometimes I can thread the cable just right and it pops out the bottom...other times...I need to bust out the coat hanger and fish for it. The worst experience I had so far is with my mountain bike. I had to route the brake hose from the back of the frame. That took me all afternoon to do.

It's something I don't fiddle with often. It's been two years since I've messed with the shifter cables on my S2 and since April (when I got the frame) on my MTB. IMO...people seem to blow this out of proportion...and it's the guys that don't have internally routed frames that do it.