I just finished spooling my reels with Power Pro. I have the old 4500, the new 6000, and the new 8000 Shimano Baitrunners. The size and line capacities of the new 8000 are exactly the same as the old 4500. The 6000 isn't much smaller than the 8000; the only difference I can notice is that the 6000 is a little over an ounce lighter and has a smaller line capacity.