To the folks who suggested Kalroth's cgminer with the xintensity feature, you have my thanks. His version is better in pretty much every way, near as I can tell. I have increased hash rates across the board. And I can run my Linux desktop on top of a 7950 doing 600kh/s without it seeming lagged.
Incidentally, I have my 7950's running with xintensity 4, gpu-threads 2, and shaders 1792. 280x's the same except shaders 2048.
Oh, and with this version, I can underclock the memory on my 7950's all the way down to 900Mhz with no change in hash rate, which saves a significant amount of power according to my kill-a-watt. The 280x's wouldn't accept anything but the default memory clock without throwing a fit, however.
Don't thank me. Thank Kalroth!
Being able to run two threads with a 7950 is a huge benefit. Hashrates up 100 KH/s, heat down 5 degrees, and power usage down a tad. My problem with the 7950 is that it seems to use 50 more watts then my 7970, and gets 30 KH/s less (but it does run hotter with the stock XFX fan).
I may need to start reducing clock speed like you did to save power.