I've been a loyal Shimano XTR user for well over 20 years. DI2 finally changed that. I just ordered my first SRAM Eagle groupset. The idea of electronic shifting is great, and I love the DI2 for the road, but when it comes to mountain biking, DI2 is way too slow, with a lot of complicated double shifts, especially when you're on undulating terrain. I used my DI2 for just under a year -- maybe 1,200 miles. During that time, I had the another of the same frame set up with XTR mechanical. The performance and ride experience between the two was not even close, but I wanted to give DI2 a real chance, so I kept trying it. Last week, after racing the Tahoe Trail on DI2, I had my shop strip the DI2 and replace with mechanical derailleurs and shifters. Mechanical weighs less, it's faster; and you have more control of gearing -- and the constant beeping!! Yes, I am sure there's a way to silence it, but it drove me crazy and made me want to apologize to everyone else forced to listen to it. From the start I was annoyed with DI2's programming. I tried to have it reprogrammed to allow me to go to higher sprockets while on the small chainring. I was able to get an extra gear or two, but the thing was still constantly driving me to the large chainring. Then if you ever needed to immediately drop to a very low gear (maybe because you come around a corner and find a big obstacle or sudden hill), you've got to allow the computer to perform a bunch of shifts, including a front and rear simultaneous shift. Ultimately, the DI2 was allowing me to go through 4 or 5 sprockets on small ring. The rest was all large. If you're running that way, why even have a double? Shimano of course offers a single setup, but the range in the back is less than ideal for a larger rider doing endurance events, so, I started looking into SRAM, which offers a wider range with the Eagle groupset. It's on the way. This will be the first mountain bike I've ever owned without Shimano shifting, and I've owned a lot of them. Thanks, DI2, you suck!