Technically that does surpass PCIe3 x2 speeds, after encoding you get 950MB/s per PCIe3 lane, so the read speed here is about 200MB/s over(Or ~10%) what's achievable on x2.
Ok? All I said was it's essentially barely faster than x2, more expensive, won't compete. It's far slower than x4 and nobody will buy it since you can get far faster drives for probably not much more money.