CrystalDiskMark is a small benchmark utility for drives and enables rapid measurement of sequential and random read/write speeds. Note that CDM only supports Native Command Queuing (NCQ) with a queue depth of 32 (as noted) for the last listed benchmark score. This can skew some results in favor of controllers that also do not support NCQ.
Benchmark Results: The Plextor M6e Black 256GB M.2 PCIe SSD topped out at 723MB/s read and 576MB/s write in the sequential benchmarks and the 4K scores were 38MB/s read and 116MB/s write. The HyperX Predator 480GB M.2 PCIe SSD managed to hit 1212MB/s read and 855MB/s write on the sequential tests and then 38MB/s read and 106MB/s write in the 4K tests.