I can say it did drastically increase the hash rate of my 7950, along with the 14.6 RC2 driver.
The 7950 went from ~ 2.2mhs to 2.8mhs (x11). It brought my 5870's from ~1.3mhs to 1.75mhs, again with the same 13.12 driver as my prior miners.
Also note I run the 7950 at a low 850/1100.
i know there is something up because i remember wlast time i had my 5850's running they only got 500kh/s while my 7750's are at 900kh/s
before the 5850's were at least 2x as fast as the 7750's