I made an interesting discovery during my own tests with the new kernel version. I had to up the memory clock of my 5870 from 200 to 350 MHz in order to achieve the highest hashing values. Another thing to mention is, that I drive a Phenom II X6 1090T with only 800 MHz for every core, due to power saving, while mining. If I let the CPU use full speed, MHash/s goes even higher, let's say 3-4 MH/s.
Conclusion: Perhaps you guys should try to raise your mem speeds + experiment with CPU clocks, too. I know it has to be a good balance, so that higher MH/s values are not eaten by higher energy costs.
Dia