It's hard to be sure but yes, at least I think so. I watched two short races (15%) with a range of values (from 500-3000) applied to about half of the cars cars and I saw a lot of behaviour that seemed to reflect the values (ie the drivers would push harder into corners some of the time, often resulting in a slight overshooting which could have both good and bad results). Since then I've driven quite a few more races (where it's harder to check what's going on) but the race results do seem in line with my expectations. Most obviously, I have had more races where an 'aggressive' driver has done better than expected - and about half of the time it resulted in a very good result, but about half of the time it resulted in one or more offs. More testing is no doubt required but so far I like BRMax a lot.
I've had much less time to test the CC error values (and I'm a very undisciplined tester anyway) but it seems to me that CC error value can only result in more errors, ie unlike BRMax it's (probably) always bad for the CC afflicted with it. That's not to say it's not also a good option for us to have though as it too could be said to reflect the driving style of some drivers, ie they were a bit lacking in concentration. If I drove in F1 I would likely have a good, ie bad, CC error rating - and that's why I only drive short races!