Granted the 4000 is big enough in most cases. However I primarily fish tidewater where:
a. the bail assembly eventually falls apart, perhaps from the salt
b. the internal gears get out of synch from the hard cranking
c. the handle assembly wears out from the endless cranking on the spinners against the tide
d. sometimes you need a reel you just gotta crank on to try and turn a chinook when seals are about.
p.s. I do like my curado which is hard to beat for the steelies.