I've had my Sertão for about 8 months and have tested it on the Continental Divide ride(Up and back), some tough local rides and am currently touring South American on it after having ridden it through central America. It currently has about 17,000 miles
I have a bunch of upgrades and I like most of them pretty well. My favorite item is the Wolfman rack and expedition panniers. I also relocated the pedals from Touratech. The factory barkbusters have been fine so far. My touratech bash guard and engine guards are on their second bike and holding up fine. I mounted PIAA 1100 lights with the 74651 brackets which strengthen the flimsy fender. I totally replaced the flimsy taillight assembly with a $7 boat trailer unit which is brighter and simpler to replace. Your rims are fine and should not need replacing. The fork oil is a bit light and I would change it to 10 weight. In the end you'll need new fork springs but at this point there aren't any on the market other than stock. The originals will last awhile but mine are diving badly now when I brake. The nice people at Wirth think they may have a spring but the need some measurements which I have yet to supply. Maybe I can just put some spacers? The stock lead/ acid battery is pretty poor, dries out quickly and a modern sealed unit would be best. I have the Touratech GPS mount which is in a very convenient location. I dont use their fancy locking device though. If you are tall enough the BMW tall seat will give you a great deal more comfort at a modest price. I lengthened my sidestand by 2.5 "s but it was not entirely a good idea as the bike is harder to mount in the taller stance. Feel free to write if you'd like to know more.