I have been messing with this myself.. but not down to 1066. I'm not sure, but I dont think tighter timings necessarily mean better performance in games. Check out this graph:
I'm not sure if this is 100% accurate, but for the most part, all of the articles/benchmarks I've seen on the topic state that there is a negligible difference between lower timings and lower frequencies vs. higher timings paired with higher frequencies... it would be preference. Normally, if you OC, you want more headroom so a wise choice would be a higher frequency module.
Another note... I've posted about this before, but never got comments on it.
I have some older 1600MHz rated RAM at 9-9-9-24.
I tried lowering the timings, but it is unstable at 1600MHZ.
I have OC'd my CPU to 4.0Ghz, with a BCLK of 191 so my memory runs at 1528Mhz... THEN I tried lowering timings and it is 100% stable at 8-8-8-21
So, I took a minor hit in frequencies (- 72MHz) and lowered my timings a nice chunk.
Nope, I would argue that it doesn't make enough difference to even bother with and the default would be fine. DDR2 days are another story though.
Yeah.. Aside from high frequencies for OC flexibility (which isn't even that big of a deal), I feel like high-end RAM is a waste of money. Even in benchmarks when they compare low-end to high-end, it always ends up being 5% at the MAX. I'd rather spend $100-150 on a decent kit and put the extra money towards a better graphics solution. But hey... it's definitely fun to tweak and perfect.