I'm at 50.9 and my understanding is rear weight is pretty important. I'm still learning setup so don't take my numbers as law by any means, but that is my current number.
My rookie opinion, Makes sense to me that if you lacked rear weight you would be loose and possibly lack bite. Too much rear would cause you to push.
Your only .6% off me, wouldn't imagine that to be too much difference. 5-7 lbs I would guess.
We run 3/8 Mile Asphalt.