A Rice in "B" weight (close to Gun builder's weight, I think) will give a light .50, a 'perfect' .40 for someone who likes a bit of muzzle weight for offhand shotoing. In .45 cal., it would still be too light for Taylor and I for offhand work, however better than the .50 but would still be a perfect hunting weight. In a .50, a "C" weight is perfect for us.
The "Leatherbelly's New Rifle" thread used the gun maker's barrel, which I think is close to a "B"? Going to a site that sells Rice barrels will give the dimensions for comparrison purposes.
What anyone prefers is simply a personal choice. I prefer like over 10 pounds total with most of that in the barrel for offhand work. For me, swamped barrels are too muzzle-light to shoot well offhand. Straight barrels give a better foreward weight. Others like nothing heavier than 7 1/2 to 8 pounds and a "between-the-hands" feel with barely 'some' muzzle weight. For them, the "B" in a .50 might be perfect.