Well it's accurate as far when the radar hits ya. There is a dead band area during the sweep (4.7 seconds terminal 12 secs ARTCC) where you don't get a hit though. Worked an F-18 once doing an unrestricted climb during a demo that was climbing almost 4,000 ft per sweep. No way of knowing what he was at in between the sweep. Seen another F-18 on tape decend from 8,000 ft to nothing in a sweep. Most likely broke up in that case. In the OP's case, +/- 200 ft into the bravo, they don't care. Might get a warning but that's about it. Even if it's several hundred feet into the bravo, you may or may not get tracked. My friend works ATL and they get violated all the time. If he's bored he might tag up a 1200 code and label him as a "violator" and follow him to the next airport and call the FBO. If he doesn't care or he's busy, he might not do anything. Varies depending on who's working.