I use the Bio 300 with a leather grip, no other added weight. It brought the static weight to 315g and increased the HL balance by about 2 pts i think, but it does make a lot of difference to the way it plays. The control is very good, but that added weight in the handle gives it a lot more power and stability.
I had my eye on getting one of these Bio Max 200G's, but thought the starting weight might be a bit too much for me. I did actually see photos of Mac using a Bio 300 with a leather grip shortly after I gripped mine with leather, but I need an overgrip as well....not enough traction with just leather.
X2 Dunlop Biomimetic 300 / X2 Prince Exo3 93