Haswell DAW - anyone taken the plunge?

With regards to memory it is somewhat complicated. So DDR4 is brand new, this is the first product ever to use it. As such as time goes on it should get cheaper, faster (not that the speed matters much) and larger modules should become available. Right now, you can have 64GB of RAM. The boards have 8 slots and there are 8GB modules. Later, there will probably be 16GB and perhaps even 32GB modules meaning an 8 slot board could handle 128GB or 256GB.
 
HOWEVER it is entirely possible that the current CPUs or motherboards won't support it. Intel lists the chip as supporting 64GB of RAM and they usually state that right. So the memory controller may only have address lines for 64GB meaning that even if larger modules come out, it might not matter unless a new version of the CPU comes out (servers are where it would matter, they have much larger memory capacity).
 
Also there is no info on when something like that might happen, what it would cost, etc, etc.
 
So unless you need more than 64GB of RAM, no, there's no issue to wait on. If you do need more, then I'd actually recommend looking at a workstation class system since you can get far more in one of those.
 
You will save some money on RAM if you wait, it'll get cheaper, but the rest of the components aren't really going to.
 
So really it comes down to if you want to spend that much money, and if it would be useful to have that much power.
 
Also to consider in your setup you'd need to move to a different OS if you want more than 16GB of RAM. 7 Home Premium is limited to 16GB by design. You would need 7 Pro, or any version of 8 to support 32GB or more.
 
Finally when looking at the CPUs, note that the 8 core CPU is substantially slower clock speed than the 6 core. What that means is while it is faster for multi-core stuff like Sonar, it isn't as much faster as you might expect. The $400 extra might be better spent on an SSD for data, rather than the 2 more cores.