Regarding the test kernels, I've only gotten to testing #3, #4 and the one built-in with nightly #6.
I took the average of 10 tests for each. The results for the speed tests:
test kernel #4 - 14ms / 6.847 Mbps down / 10.143 Mbps up
kernel in nightly #6 - 15.4ms / 6.966 Mbps down / 8.034 Mbps up
test kernel #3 - 12.6ms / 6.214 Mbps down / 9.378 Mbps up
According to Roach`, the difference is the latest drivers are on #4 and that if it doesn't make a difference in the tests, then it's not the drivers.
There are many other factors contributing to one's WiFi connection speeds, but for me I guess it's safe to say it isn't the drivers. I'd suggest to give this a try before settling for the kernel. For Roach`, test kernel #4 works best, for me I'll be sticking with the one he put in nightly #6.
EDIT: Apologies! I just realized that when I tested #4, it was connected to a server slightly further from my location. I redid the test and the results reflect above. I guess test kernel #4 is better. The reason why the download speeds are a little lower than nightly #6 is because I did more tests on #4 (I couldn't believe how much higher it was than the previous test since the locations are only a few miles apart) and that brought down the average. Take my results with a grain of salt, but for me, I can honestly say that I prefer test kernel #4.