Innitial impressions are positive but not really earth shattering. I would be interested to do a back to back comparison with the Ohlins fork kit to see how it compares. The RacingBros fork cartridge kit brings more sophisticated hydraulic damping than the Ohlins, but I believe the Ohlins kit uses stiffer spring rates.
The innitial impression in the garage from simply holding the front brake and pushing down on the front brake was that the forks were far stiffer than stock. The stock springs are so soft you can nearly bottom the forks just by shoving down hard. The RacingBros kit brings about resistance I am more familiar with thanks to riding dirt bikes. I have about an hour of ride time so far, and I can honestly say that the wollowing in the front end is gone when turning through intersections. The front end dives less during braking and its more noticeable during light to moderate front braking where the stock setup would still dive pretty aggressively. The RacingBros setup will still use up a lot of fork travel when braking very hard but I would have to assume its less than stock. On square edge bumps, the forks take the sting out of the hit, but I do believe its sending more load to the rear shocks now thanks to not blowing through. Im feeling more through the seat than before but a lot less through the handlebars.
Regardless of what fork upgrade you choose, the imporant thing to keep in mind is that this bike has less than 5 inches of suspension travel on the forks and less than 4 inches in the rear. There is no getting around that, you cant make it ride like your on a pillow and still have bottoming resistance. I believe RacingBros went for improved ride performance while still keeping comfort in mind. If this were a full blown race setup with track usage in mind, then it would be far too soft. For the your average street rider who is looking for improved performance without having the front wheel deflect and skid over small street hack, its a good option.
Overall I would give this setup an 8 out of 10. Its absolutely an upgrade over stock, but keep in mind that there is only so much you can do with 5 inches of suspension travel. For those who dont know, a well setup bike will already be using around 33% of the travel withe the rider just sitting on the bike. So while riding, the Rebel really ends up with about 3.5 inches of travel to deal with all the chatter on the road.