Offering 2% more performance in our real-life benchmark tests, Crucial's new M550 SSD is a reasonable upgrade over the M500 SSD. The 2% gained roughly puts it on the same level as Samsung's 840 Pro SSD and OCZ Vector. However, it is not the fastest drive on the market as Toshiba's THNSNH GCST Series is still faster. Overall, I'm pleased with its performance, and the performance differences in this market segment are too small to be noticeable during normal use anyway. It's also good to see that Crucial has done away with overprovisioning, which allows you to use the drive's full capacity without any loss in performance.
Marvell SSD controller technology has been used on many drives in the past, and we've never heard of any horror stories involving it, so its use is a smart choice by Crucial as it ensures your data stays healthy. You can also use the M550's encryption features, which are complete as they including AES and TCG/Opal, if you need secure data.
The M550 512 GB is currently available online for $335, which is a really good price as it is cheaper than most comparable options on the SSD market. With that said, the Crucial M500 can be had for $229 - a huge price difference. The M500 uses overprovisioning, though, so it only offers up 480 GB instead of 512 GB, like the M550. Still, pricing clearly favors the M500. I'd rather go for the M500 due to its amazing price, even though its capacity is slightly lower and its performance 2% less. Another choice could be competing drives from Samsung - the 840 Pro and Evo come to mind.