I bought this SSD 240 go for a late 2009 27p Imac intel core2duo (go the 120 was too small). I did not want to dismantle the mac at the moment so I placed the SSD external enclosure firewire 800, and I cloned the original disk (+ 5 system users, leaving the data on the internal HD) via Carbon Copy Cloner shareware. No problems with Apple formatting tool: the SSD is recognized immediately, and CCC support it without partitioning Mac OS Yosemite. I think then put internally in the Imac.
Appraisal: mac even faster via this external firewire: 22s start instead of almost 3 min 8s logons and change users 1 s. The system certainly win again by placing the SSD in Mac.
This SSD is fast enough in my opinion and is well advertised with good compressible data rates 240 GB version. The OS is composed of a multitude of compressible files, and loading is quick (even firewire).
Attention to critical comments about the speed they probably rely on incompressible data tests (eg video), or the characteristics of SSD are expressed default with compressible file transfers, so much higher: it is the case for all SSDs. These tests do not give the maximum values of SSD, but the minimum.
It seems true that this record has fleas with a burning bigger size, and therefore a bit slower (but this is visible to the user, not?). Tests show that it takes time to regenerate if it was filled to 100% twice, but this is the case with all SSD with SandForce controller apparently; Marvell controller has better results in tests, especially during regeneration of SSD without loss of reactivity over time. To book an OS and not a data storage rewritten frequently (especially video data or audio incompressible).
The support Kingston informs me that there is indeed a garbage collector on the SSD so that the disc regenerates in the background. Do not activate the trim on the OS that is not useful (so no need to trim enabler either). We must let the drive periods of inactivity to regenerate without the disk by the standby system.