MPG spoke with driver expert Tim Standing of SoftRAID today about TRIM for SSDs and OS X Yosemite, to better understand the issue.
Online reports are that OS X Yosemite no longer supports TRIM for non-Apple SSDs. This is true.
Furthermore, use of a tool that enables TRIM on an SSD causes the system to become non-bootable, because Yosemite sees that a key 'kext' has been modified.
Users who have not upgraded to Yosemite that have used a TRIM-enable tool should be aware of this, and revert before upgrading to Yosemite.
MPG has not recommended SSDs that need TRIM for various reasons, but this is the latest development that really makes such SSDs unpalatable. OWC SSDs do not need TRIM, and MPG has been running them for years, thus avoiding the issue entirely.
Checking whether TRIM is enabled
Choose Apple menu => About This Mac => System Report