What is sustained write performance?
I have found sustained write in Crucial drives to be very far off.
Example: two machines, roughly same spec (AMD quad core A4), one with Cruicial drive and one with Kingston, upgrade from Debian Weezy to Jessie. The test writes a couple gigs of data (first downloading packages, then unpacking) in a mixed pattern (random write + a lot of sequential large volume writes).
The Crucial - upgrade took > 2 hours. The Kingston one - under 15 minutes.
If you benchmark them, they show up fine. If you start using them for real - not so much, there is a write performance "drop off a cliff" under load. I am definitely not bying them ever again.