These are a fine epic replacement for a ranger IF---- you don't use them all the time. When using a bow - you would want Swiftwind in your off hand. Specially if you are doing an AOE fight. So if you are doing your ranger duty and fighting from the side or behind --- then this is the optimum choice. But if you are tanking for an exp group then the bonuses of Swiftwind would outway the greater Ratio.
We recently got one of these for a Ranger that - I think had epic - and A Warrior that really needed a haste item.