OK. A lot of what's going on here is that when you run a bigger case capacity, you can do the same work as a smaller case at less "peak pressure", which means lower felt recoil, less stress on the gun, etc.
That's where the 480 comes in - it was an attempt to get a bit below .454C power levels and with a LOT less wrist stress.
To understand why this works, John Linebaugh has written a ton of material on why he prefers .45LC to .44Mag. His documentation and evidence is at:
http://www.sixgunner.com/linebaugh - esp. everything under "gunnotes".
This is basically a look into Linebaugh's early work, and explains why he went towards the .475Linebaugh and .500Linebaugh later. The .480 is basically the .475Linebaugh shortened a bit.
That said, there's a major disadvantage to the 480 - there are no "under-power factory loads", so no cheap practice unless you're a reloader.
With .454C, you can get Cowboy-grade plinking loads fairly cheap and at very low power levels, and go up from there in stages. The best factory 45LC+P matches or slightly exceeds .44Mag ballistics while recoilings...not exactly "less", but with lower peak pressure you get more of a "drawn-out-push" versus a "sharp snap". See also Linebaugh's stuff in the link.
