Suspension is usually a case of try a bunch of things to see what works under what conditions. Even the calculations are iterative, painful, and a continual compromise if you are trying to set up the perfect ride rate for both a 15 degree bank on a bumpy road, or a 7 degree bank on a smooth road/track.
Changing the distribution, and being able to tune for different conditions/tracks is one of the main benefits of the roll bars. Unfortunately when you are talking about already being neutral, on the street, and not being able to judge when it lets go, I tend to also think about tires (some tires are well known to have less well defined breakaway points and when they are gone... they are gone), and other possible issues.
But to keep it simple and as per the original question for a roll bar related solution, I would say that you have the right train of thought to decrease the roll moment in the rear. Or at least I would want the driven wheels to be more evenly loaded to perhaps power myself out of a situation/corner... and that can be done by reducing the stiffness of that bar on the driven axle. Try a simple adjustment if yours are adjustable, try a stock bar, try no bar.... see what works.