I popped a 1055T into my Gigabyte 785g AM2+, clocked it to 3360MHz and compared it to an unlocked 550BE when transcoding (a Family Guy episode) in Handbrake (using GSkill DDR2 at 800MHz).
It scaled in almost a perfect linear fashion, but I suspect you are more interested in a comparison with DDR3 ....
And I think it will make little difference, if any.
edit: The volts also scaled but I had under-volted the 550BE to around 130w at load. The 1055T ran at a bit less than 188w at stock (which was amazingly similar to the 550BE before I under-volted it).
I didn't have time to under-volt the 1055T before it went out the door --- if I secure another I'll give it a try.
--