well, I have pretty much zeroed in on 950 pro or maybe even a 960 pro 256gb for OS, for that I am going to wait till late Nov or Dec to for the prices to stabilize and maybe have additional checkout coupon with AMEX MC or whatever...
For games and stuff I will stick with 500GB 850 EVO for now, *might* switch to a 1TB M.2 PCIe drive is I get a good deal, but that on the back burner. Newegg does not seem to carry 1TB version of 600p...
Get in on this deal, then sell Watch Dogs 2 if you don't want it.
The 960 Evo 500GB drive has identical 4K random read/write to the 960 Pro model, as well as 200TB of endurance, which is close to 3X the endurance of the Intel 600p 512GB SSD.
The discounts (10% employee + 10% coupon code), with complimentary Watch Dogs 2,
apply to the entire Samsung line of SSDs with 500GB or greater capacity. The game doesn't come out until November 29th, which means it should be possible to get a good resale value on the U-Play coupon code. Alternatively, you can just buy the 960 evo/pro 250/256GB with the same 10%+10% discounts but won't get the free WD2 game.
Another option could be for you to sell the 850 500GB Evo for $80-100, buy the 1TB 960 Evo, sell the WD2 game for $30-40. Your net upgrade would be roughly:
$479 * 10% off employee discount * 10% off unique coupon code discount x state tax (let's say 6%)
- $80-100 for resale of the 850 EVO 500GB
- $30-40 for resale of Watch Dogs 2 game coupon
= $270-300 net upgrade to a 1TB 960 EVO NVMe PCIe. Not bad.
BTW, 600p 256GB "Open Box" is available for $73, $148 for 512GB, looks like things are not going well for them

But it's definitely worth at that price
The deal I linked above would net a 960 Evo 500GB brand new for $215 or so, and then after selling Watch Dogs 2 for $30-40, it'll be a net cost of $175-185. There is no way I'd pay $148 for the 600p 512GB under such a scenario. The 960 Evo isn't as good as the Pro, but 200TB vs. 72TB endurance, and the Evo still retains the 5-core Samsung Polaris controller from the 960 Pro I believe.
The 960 Evo is still better than the 950 Pro, and the 600p is nowhere close to the 950 Pro in performance.
You WANT to use that M.2 slot, but you DON'T want to be swapping out one M.2 for another if you have no way of using the spare.
Stop buying overpriced and under-featured Asus motherboards.
Meanwhile Gigabyte Gaming, ASrock Extreme/Professional and MSI Gaming series have 2-3 M.2 slots.
Asus is the KING of feature GIMP, charging and arm and a leg for features MSI/Asrock/Gigabyte have on mid-range boards. Not only that,
Gigabyte offers PCIe 32GB/sec M.2 RAID on a ~
$150 range board!
Delivering up to 32 Gb/s data transfer speed per connector, the dual M.2 provides an ideal storage solution as it also supports RAID modes.
Gigabyte's latest Z170 boards even allow triple-RAID of M.2+U.2+PCIe:
http://www.gigabyte.com/products/product-page.aspx?pid=5811#ov
This feature is available with Gigabyte on a
$170 board.