7-7-7-21 should work fine. You can even try to lower.
The DDR3-1600 method you read is no problem for the memory controller. The voltage boost helps the CPU support DDR3-1600. Only DDR3-2000+ will seriously stress the memory controller.
The timings are fine. When you lower frequency to 1333Mhz you should be able to lower the main timings by 1. Which means that, indeed, 8-8-8 turns into 7-7-7. If you overclock your RAM you should be able to lower the timings by 1 again easily. Which would bring you to what I've done - 1333Mhz 6-6-6 timings on RAM that originally runs at 1600Mhz 8-8-8.
I don't really see how their "fix" to the memory controller is going to work, though. If anything, you're actually stressing it further as you're adding voltage to it. Unless memory controllers are a whole lot different than other PC parts then "too low" voltage won't kill them. Generally, temperature is the main reason things in a PC die. Increasing voltage obviously increases temperature.
From what I've heard stepping C3 processors ( I'm assuming yours is a C3 ) are somewhat better at handling higher memory frequency but I wouldn't tempt fate. Not too long ago we had someone start a thread here and his problem seemed a lot like blown memory controllers.
Myself, I probably have a very weak IMC ( Integrated/Internal Memory Controller ) on my C2 processor as it's not working at all when you increase the CPU-NB voltage.