Sandra is an oldie but a goodie as far as memory benchmarks go.
Here we can see that the Corsair PC4400 Pro at 3-4-4-8/1T does remarkably well against DDR2 running at 876 and 933 MHz as well as the OCZ PC4800 memory running at 2.5-4-4-8/1T. It performs solidly even when running at 3-3-3-8-2T and 3-4-4-8-2T.
The Sandra CPU tests are not really affected by memory speed, but I thought you might be interested in seeing them.
WinRAR
I really like using WinRAR to rate both processor and memory performance as it seems to be about equally affected by pure processor speed and memory performance.
Here the PC4400 Pro is only beaten out by 4.5% so it is fair to say that running at 550 MHz with 3-4-4-8/1T or 3-3-3-8/2T timings it performs very well. It even beats out DDR2-933 on a 4.2 GHz D 930!