Conclusion
Despite having only four NAND flash memory chips on a tiny 1.8" PCB, the mSATA m4 managed to keep pace with larger 2.5" drives, including Crucial's original m4 and most of the 2.5" SandForce SF-2281 SSDs. In fact, in both of our real-world application tests, the mSATA unit delivered the highest or second-highest score, succumbing only to the OCZ Vertex 4. Likewise, the drive fared decently enough in our file copy tests.
Given the relative rarity of high-capacity 1.8" SSDs and the m4's solid track record, Crucial could have likely gotten away with charging a slight premium over its 2.5" iteration. Currently, it seems the 1.8" m4's primary competition comes from SandForce SF-2281-based drives such as the Mushkin Direct Atlas Deluxe mSATA 240GB, which costs slightly more at $230.
With high marks in both price and performance, the m4's reliability is the only factor that remains unaddressed, and in my opinion, Crucial also scores very highly here. Since its release, I've owned many m4s and all of them remain in use today with nary a hiccup. Crucial has been quick to patch bugs and they've worked hard to hone the drive's performance. From what I've seen of the company's support, the m4 would definitely be toward the top of my list if I were going to invest in an SSD today.
Pros: Tiny form factor, big on performance. Crucial's track record on SSD products is excellent. Can be installed directly on mSATA motherboards. Miniature tech that works this well is simply amazing.
Cons: If you don't require the small footprint, there are other equally attractive SSD options on the market.