just my thoughts....you'd have to run several races using both systems....the "official" one would be the current model....then you take the lap times during these "test" races and carefully look at the times posted and see where the variance would be and see where the fall off and when the gains are the highest. this would be very time consuming but it would have to be done with the racers none-the-wiser....if you let them know in advance that your checking this, then you'll get the sandbagging right from the start.....but! if you take the time to carefully review the times and set your "DQ" level appropriately, then i think the bracket racing could work. along with that tho, is one thing that i totally disagree with.....
if you are listed in a bracket and you break out, then some advocate moving you to the next fastest or the fastest class. this is where i disagree and will get blasted....if you win or are subject to teching and your motor is declared illegal, you are DQ'ed....and you don't get a second chance. the same philosophy should be used here....if you go out and run and break out, then you're dq'ed....no exceptions, no excuses....you don't move forward to the next class or the fastest class. moving forward is unfair to the ones that went and run thier best to be placed in the correct bracket...
you take a chance when you sandbag and there has to be consequences when you try to buffalo your way through to a slower bracket. but this comes back to running several races and getting those times so that you can get a good idea on what it will take before a racer is dq'ed for breaking out. it might only be as much as 2 tenths, but like Weddle Racing says, varying track and weather conditions can cause racers to lose time and then again, those same conditions can cause a big boost in lap times.....
it's a fine line to attempt bracket racing, but if done right, then your going to have some very close racing! the other thing is that you'd have to time the karts every race.....because one improvement made today could change me from the slowest bracket to the fastest......
just my thougths....i like the idea of racing against others within my lap times....might mean the difference between the same people winning week after week and having new winners every race......