Go for the M4 yes there may be one or 2 out there faster, but none more reliable, and they have just had new firmware out(0009) which makes it faster and smoother ... and they also go for around £135 which is cheaper than the one you asking about, and its 8 GB more as they come in at 128GB.
There at £132 for a M4 128GB
The 128Gb thing is a bit of a swiz, my Corsair is 128Gb as well, but it will not use it all. From what I have been reading the drives are still classed as 120Gb as the extra 8Gb is left to take over when the memory starts to fail.
My corsair is fine, it does what I want, but thanks anyway
Desktop machine now powered by windows 7 pro 64bit , laptop by ubuntu
On ADSL24 using C&W network.