Paul P :
I was happy just to have found memory that appeared to be suitable, I should have taken more time to research though I'm jogging as it is, trying to upgrade while busy with a lot of other things.
Well, DDR3-1600 ECC memory only just came onto the market, this year. I've been watching. So, you're already pretty close to the leading edge, there.
And the Crucial RAM I cited is literally the only CAS 9 stuff I've found. So, you'd have really had to hunt around for it. I just got frustrated seeing latencies creep up faster than speed, especially when the enthusiast-oriented stuff was timed so much more aggressively. I just figured there ought to be something out there better than CAS 11 and kept searching until I found it. I'd still like to find CAS 9 in a single-ranked DIMM, but it probably doesn't matter.
Paul P :
According to the link I may be able to redeem myself by overclocking the memory
though I guess that might kind of defeat the purpose of using ECC memory...
First of all, going from CAS 11 to 9 is only worth a couple percent, in the most extreme cases. For most workloads, the difference will be tiny or immeasurable.
Now, if you do want to overclock your RAM, I doubt ECC will overclock as well as non-ECC, but the ECC will give you an extra safety margin. Normally, people overclock until their machine becomes unstable. But with ECC, you could overclock (or just tighten the timings) until you start seeing single-bit ECC errors in the logs, and then dial it back one setting. The beauty being that single-bit errors are correctable, so you can have the peace of mind of knowing whether you're close to the edge or not and being able to monitor it over time.
However, I don't overclock, at all. I even underclocked a fileserver, once. For me, another 15% or 20% isn't worth the cost of data loss, corruption, or instability. That's why I bought a Xeon w/ ECC RAM, in the first place.