I also heard that the DFI is the only mobo that allows you to change the voltage for the memory.
No DFI is not the only motherboard to allow you to change memory voltage. They probably allow some of the highest adjustments, but just about every K8 board allows you to bump up the voltage to some degree.
You should get some of those G.Skill LA's, technically they are low latency high performance RAM, but that means it's quality parts and will OC like mad. You should be able to get upwards of 275MHz+ if you just go at it the right way and read up on OC'ing basics if you don't already know