Take this for what you will, as I road race my FR125, which keeps the revs down. At the end of our season, we have the top end freshened, which, frankly, is probably overkill for us. Apart from that, we keep it clean and monitor for wear of the RAVE bellows, fuel pump diaphragm and clutch. We’re in the hunt for our regional championship each year.
There are always people who complain. For example, the same people who moan about the diameter of the carb being too big are the same people who would complain if that was ever changed requiring a carb change. It would be wise that the Rotax you purchase already have the full clutch update (clutch hub, clutch drum, steel water pump/ balance shaft gears), air box and coil, so that you don’t have to incur the cost of the update.
Front brakes are not required for the FR125. Sometimes they are flat-out not allowed: sometimes they’re allowed with a weight penalty. My advise would be that, if you are not going to be road racing or running a shifter within the next three years or so, take off the font brakes and sell them.