Di2 works really well. Though I was quite negative about charging batteries for my bicycle, I finally got tired of having to readjust the shifting every other week as there was a little wear here or there. Using the long arm Di2 rear derailleur you could shift a 34 tooth. That is the same gearing as a standard triple.

The only dangers with the battery is the damn things last so long that it is easy to forget to charge them. They shift perfectly reliability time after time.

That particular Madone is NOT a good target though. It was never designed to have internal wiring and although you CAN get the internal wiring to work, you would probably have to use an external battery. These are fine if you know that you have to have the EXACT external battery holder for the specific group. There are three or four and the entire system looks dead without the proper battery mount.

It also requires practice to use. That shouldn't be a surprise but it usually is. Just like you have to learn when you cross from Campy to Shimano to SRAM, you have to learn either Di2 or the SRAM wireless equivalent. The charger that plugs into your computer and charges an internal battery for your Di2 this will configure your system a number of different ways. I started using light long finger gloves and it was pretty difficult. Then it got warm for a couple of days and I could practice with short finger gloves and found what to expect. The other days I used heavy gloves and could easily shift.

To tell you the truth I can't see any more advantage of manual shifting anymore. Cables slip, the shifting cogs in the levers wear or get dust in them and stop shifting, the derailleurs have to be readjusted now and again. And the front derailleur in particular has to be micro-adjusted as you move across the cogset to keep from wearing it. Di2 self-corrects so all you are doing is shifting.

As others have said, in general it is best to buy a bike with the Di2 installed. It is a pain in the butt to buy the correct length wires (6 to 9 at $25/each) and getting them to work. Now perhaps Trek has a method for installing an internal battery but they don't for my 2012 6.9 and told me I would need to drill a hole in the frame and glue in a special wire entrance/exit in order to mount the external battery mount. That also means that you have to buy a separate Bluetooth interface. The latest internal batteries have Bluetooth built into them. And you need that to connect with your Garmin to show speed and cadence off of your back wheel instead of the front one thus screwing up the bike aerodynamics.

I suppose you bought that bike complete. But the disk brakes are a snap to bleed once you know how. I accomplished it in 30 minutes from scratch and it worked perfectly. I did an entire external wiring which is something of a problem since you have to be careful with the wires and get their length very close to perfect. Nothing would work until a shop guy printed out a chart off of the Trek manual site that showed the correct and NOT interchangeable external battery mount and then everything fired right off and worked instantly.

My judgement? I won't go back to manual shifting. As for Ultegra or Dura Ace? The Dura Ace levers weight nothing at all. But everything else is pretty much the same weight as Ultegra and I can't see any point in Dura Ace other than the levers.