More product testing. This is hard work! Nox Composites Skyline rims with some fat, Soma Grand Rando 650X42 tires on them. Dynolyfe proves to be worth it (Son28). No more battery lights for me (Luxos U front and B&M Toplight rear)! Yes I know that's ironic considering the bike has Ultegra Di2, but I don't have to charge that every couple of days. I always head that the spread on these German lights were better than the typical batter light, including the Light and Motion Taz 1200 I used to have. All it took was one night right to prove correct. The beam is far more suited to road riding.
I went with SKS Longboard fenders this time. 650b fender options aren't as vast yet. These are nice, but could use a little more length on the backs.
Disc brakes? Yes, I always hated that rim scraping sound in the trails. Also, I still have 700c wheels for this bike so I can always strip the fenders and make it a dedicated road machine. It would take about 10 minutes. For now, the is the setup I'm keeping together. It give me all the riding experiences ranging from 100% road to hopping into some easier singletrack. The bike is pretty quick in both environments.
Don't forget to add a front flap to your rear fender!!!