I realize this is a MacBook Pro thread, but thought I'd share my experience using two M4s in RAID 0 on my Mac Pro.
1) Screen grabs: see below
2) Hardware overview
- 2012
- MacPro5,1
- Quad-Core Intel Xeon
- 3.2 GHz
- 24 GB DDR3 ECC 1066 MHz
- 4.8 GT/s
- 3 Gigabit/1.5 Gigabit
- TRIM: Off
- OS X 10.8.2 (12C60)
3) Info on the Crucial M4 SSD
- 512 GB (x2)
- Bays 1 & 2
- Firmware version 040H
4) RAID 0
I ordered both of my M4s from Amazon, but one came with the latest firmware (040H) and the other with the previous (010G). I didn't notice until after I created the RAID set and cloned my system back 😱 As a point of information, I searched up and down today for any confirmation whether or not it would be possible to update the firmware on a drive while still in RAID (which led me to this thread). I didn't find anything terribly useful, but I gave it a shot anyway and can now confirm that it works just fine. After booting off the ISO CD, it recognized that one M4 was current and offered to update the other. Easy peasy.