Eps wiring is just that, a few waterproof wires, just like Di2.
You can run it external of course.
You can use zip ties at strategic locations, or the Shimano style cable covers (available in black, white or grey I think)
Here is a build using zip ties:https://www.facebook.com/media/set/?set ... 030&type=3
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You REALLY should not be picking a groupset based on visual styling. That is like picking a painting on how it smells or a poem on how it tastes.
If you just wait a few months I bet the old Di2 prices will fall off a cliff (or if you buy now you will see your re-sale values plummet).
The two systems provides different levels of tactile feedback.