Since this is a critique, any particular reason you are opting for crossfire? I realize that without going for a Fury X or an R9 390(X), you can't get higher end GPUs from AMD at this time, but it always strikes me when someone goes for Crossfire / SLI before getting their PC in to be sure they indeed do need or want the extra performance.
A far more important question, what resolution will you be playing at? If it is UHD, or even QHD, then the crossfire setup makes sense.
Note: Doing with a larger SSD, as JWCrellin recommended, is something I back 100%. I love my Samsung 850 Evo, it is easily the best component in my PC (Way better than my CPU or GPU in terms of my levels of frustration when using my desktop). I'd look into if you prefer SATA or PCIe (I assuming that someone going crossfire is a power user, and might care about the differences). The Crucial MX300 is a SATA drive, as if the Samsung 850 Evo. There are options like the Samsung 960 Evo which are PCIe, and a price premium, but definitely outclass those two SSDs for power users.
Let me know what you think.