Both the Samsung and the Apple SSDs are just a bad fit for a machine like this. For a non-I/O bound workload it's paying money for nothing. For a read-bound workload, the machine has 64GB of RAM, so you'd need a working set larger than that to have to care, and that's pretty rare. For a write-bound workload, at those speeds, you're going to melt a consumer-grade SSD and need an enterprise one. So you don't want the faster one in this machine; either it's not worth the price or it won't survive that amount of write load.