You can get a 250GB 970 EVO for 7 dollars more, so why wouldn't you? On a laptop I can't imagine most people really need a 500GB drive unless they're storing their game files on the same drive, which might be a really bad idea. I'd put them on a secondary drive and then also back them up on an external drive.
My 970 EVO seems to make everything faster, not just sequential operations. Which it should, since the random OPS are about 200,000 OPS higher than the next closest SATA SSD. I'll concede that not everything is going to be faster using an NVME drive, but it sure as heck isn't going to make ANYTHING slower.