I had a mech bike I wanted to convert to electronic shifting after I built up a new bike with Di2. Etap was really the only choice because Shimano's solution if the bike isn't set up for internal routing isn't pretty. I was surprised to find out I really, really liked eTap even though I'd been a Di2 fanboy. Now, I'm looking for a reason to swap out the Di2 for eTap on that bike too. Zero problems, it shifts super smooth and since it's my travel bike, the lack of wires or cables makes packing it super easy.

J.