Electronic & Hydraulic Shifting (Di2, Ui2, customisations)

Seconding this. I previously had the Ultegra R8070 hydraulic shifters for a few thousand km's but recently decided to give the RX815 GRX Di2 shifters a go, after long hesitation. I was concerned about the longer bracket body compared to the Ultegras but there were so many positive reviews I wanted to find out what all the rage was about. Having now done a few longer rides with them, I regret not having done the swap earlier. The ergonomics is absolute bliss. I never thought that the feel of the shifters could have such a huge impact on ride comfort. Don't get me wrong, I was fine with the Ultegras but the GRX is a vast step forward. With the GRX I can easily wrap three fingers around the shifter and still have enough room for pivoting the brake lever with just my index finger. Can also wrap four fingers around it when cruising along. Braking is superb with the Servo-Wave (which the R8070s don't have, despite it being mentioned on the box of some of the first units sold; that misleading label was later removed from the box).

The latest 12-speed Di2 shifters also have a longer bracket body and I reckon the feedback from riders using those GRX shifters probably played a role in it. For reference, I'm wearing size 8/M or 9/L glove so not very large hands either, which was a reason for my hesitation with regards to the longer bracket body.

The extra hood buttons are differently positioned on the inside of the hoods rather than on the top, but I'm using them for controlling the bike computer which happens rarely so not a big issue even though I think the buttons are better positioned on the R8070s.