Originally Posted by
donrhummy
I would go Ultegra Di2. SRAM Red with Yaw is very finicky. It only works with specific chainrings and cranksets and is very touch to setup perfectly. The biggest plus for Ultegra Di2 is the front shifting. It shifts to the big chainring under load better than SRAM Red does with no load.
I went with SRAM Red, mostly because of the 2 pound weight advantage.
In my experience, the shifting is great. It's better than any Dura Ace group I've had (although the last generation of D/A I've used is 7800). The Yaw red FD worked fine for me with an FSA crank, which I used while waiting for the New Red Quarq crank. With the Red crank it shifts fantastic. It took a little attention to detail, and following the instructions specific to the Yaw derailleure to set it up. But a year later, it's still shifting fine, without so much as turning a barrel adjuster in 12 months.
From all accounts, I'm sure your right that Di2 shifts better up front under load, than Red. However, Red shifts pretty darn well, so I'm not sure how much better it gets.
So for me, great performance, 2 pounds lighter, and the aestethic of a manual group, and one less battery to worry about (admittedly a minor worry) trumped slightly better electronic shifting.