If you aim beyond 200 MHz FSB, I'd go with Corsair 3500C2 which is spec at 6-3-3-2 memory. Other memory like Kingston HyperX 3500C2, OCZ 3500C2, ... are spec at 8-4-4-2 timing, which may not be able to run at DDR 434 MHz at 6-3-3-2 due to module variations.
For bandwidth benchmarking, 3500C2.5 @434 MHz DDR would score higher than 3200C2 @400 DDR. 3500C2 is about 9% faster than 3200C2, and 4% faster than 3500C2.5. So 3500C2.5 would still be faster than 3200C2 by a few %. It will lose a bit on latency when the processor has to get data from memory if there are lot of cache miss.
I am in similar situation, looking for running at 230+ MHz FSB, at which even Corsair 3500C2 may not have enough headroom to do that. I am waiting for 3700C2, but don't know how long the wait is. Samsung, OCZ and GEIL have 3700C2.5 memory for that speed, but I am not sure they will be able to deliver x-3-3-2 timing at 2.8 V, unless you want to boost the Vmem to try.