Great link, thanks!

More questions now. This will be an interesting project to puzzle over for the next month or so.

My 2010 Tarmac frame is not set up for internal wiring. But, the frame was recently broken, repaired, and stripped, so I would be willing to experiment with drilling it out. Shimano even makes grommets for retrofitted holes. I'm thinking I would drill out the cable stop rivets. It's appealing as a tinkering project.

Or, stick with the etap plan.