It's important that you understand what those numbers DON'T tell you.
That number quantifies how flat the speaker measures -in a vacuum, which is a useful metric for sure, but you also have to think of the real-world scenario. There is basically no difference between 6.2 and 6.31 in practice, especially after you put the speakers in a real room and the response becomes much more "wiggly" as you go lower in frequency. That score is not accurate enough for us to care about these little decimal differences (they are both very good in this regard). If you see a speaker ranked at 6.2, and another ranked at 3.5, that's a large enough difference to be very significant.
Secondly, that number doesn't take into account maximum output and distortion. The Genelec 8030C is a smaller speaker, with a little woofer and tweeter, that's it. It can only play so loud. If you want speakers for a large room, the little Genelec won't be able to play loud enough for that space, compared to the larger KH310, with its much larger woofer and dedicated midrange driver. Of course, subwoofers can always help, but the 5-inch woofer of the 8030 would still be responsible for the entire range above the subwoofer and bellow the tweeter crossover, something like 80-3000 Hz. In the case of the KH310, because it has more drivers, each one is responsible for a smaller frequency range, which helps the speaker play louder and with less distortion.
Lastly, the score doesn't take into account how wide or narrow the directivity is. Not the main issue in this case, but you should be aware of it.