Plextor M3 Pro
If we concentrate only on the hardware then we don't see much difference between the M3 and the M3 Pro. The new Pro model is also based on the by now 2.5 year-old Marvel 88SS9174 controller and 24nm Toshiba ToggleFlash chips. The controller is supported by 512 MB DRAM cache. The only physical difference is that the M3 Pro is somewhat thinner, it's now 7 mm thick. That allows it to fit into smaller laptops as well.
The main difference can be found in the firmware. Plextor remains tightlipped about exactly what has been changed, but the performance has been increased in theory. For the M3 256 GB Plextor claimed 510 MB/s read and 260 MB/s write speed. For the Pro these values are 540 MB/s and 420 MB/s, respectively. The random performance should also be increased according to Plextor, from 70k 4k read IOPS to 75k 4k read IOPS.
The M3 Pro is available in three versions, 128 GB, 256 GB and 512 GB. The average prices are £154, £285 and £539, respectively. Now that we were getting used to SSDs in the sub-£1 per GB range, these prices take a little getting used to.
The factory warranty is still five years, and the SSD comes with a bracket and migration software. Plextor again claims one of the lowest failure rates of all SSD brands, but this is difficult for us to verify.