Maxwell Render | Official public forum

Dear all
I'm about to order a new PC with an new i7 extreme (10 core probably).
I have to option to chose three different speeds for the DDR4 RAM:
2133, 2400 or 2800 MhZ
Since the prices for a higher frequency are higher, I asked the resellers and they told me that not many programs can even make use of the higher frequency and that it would be completely sufficient to get the slowest speed (2133 MhZ).
Does anybody have experience with the memory speed? Does it make a (huge ... or any) difference with Maxwell Render?
Thanks

I would just get the fastest for future upgraded software that will make use of it.
If you get the slowest then V4 comes out next week and boasts of making 2800mhz useful then you would be set.
These new broadwells might be the best for a while to come so you might want to make your new machine upgrade-proof for while.
Just my little penny's worth.