Brakes... Single best reason to go 450.
Go C&C if weight is an issue.
I find it interesting that in discussions about the p/u versions of the 350/450, people get all hung up on the 500# difference, or whatever it might be that week, yet, half the threads about weight on this forum our about people carrying well more than the stated/listed/advised limits. Yet narry a whisper about stopping said weight.
A maxed out truck is just that; everything is at the limit, not just the capacity. Personally, I think stopping is a whole lot more important than how fast I can get up that hill.
To each his own.