ScienceMark 2.0, Pifast
Let's take a look at bandwidth and latency first.
Nothing much between two nForce3 250 and a VIA K8T800 board. That's not entirely surprising given that the memory and DRAM controllers are extraneous to the chipset.
Again, latency considerations are generally taken out of the hands of manufacturers. What they need to concentrate on, then, is ensuring that BIOSes allow maximum adjustment. Performance shouldn't be a deciding factor at default speeds.
Less than a second separates the three boards. Chaintech's ZNF3-250 is the meat in an EPoX sandwich.