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I have the following KingSpec mSATA SSDs currently in my Macs:

MV-32 (Black) via mSATA/PATA IDE JM20330 adapters on ATA/66 and ATA/33 (iBook)
- TiBook 867Mhz, Pismo 400Mhz, iBook Clamshell 366Mhz

MT-64 (Black) via mSATA/PATA IDE Lindy/Addonics adapters on ATA/100
- PowerBook G4 12" 1.5Ghz, PowerBook G4 17" 1.67Ghz

MT-256 (Black) via mSATA adapter on SATA II (3.0G)
- iMac 21.5" 2009 (2x 3.36Ghz)

The 64GB and 256GB are the same speed. The 32GB is quite a bit slower, so I've installed them in the ATA/66 and ATA/33 Macs.

In every case, the SSDs have made a huge improvement over the HDDs and have been rock solid so far. It has been 6 months since installing in the PowerBook G4 12" with regular use.

I did try the 256GB SSD in my G5s and it was about twice as fast as the HDDs (Maximum throughput around 150MB/sec) which added up to great boot times and snappy app launching. But for the most part, the SATA HDDs operate reasonably enough in the G5s (around 70 - 80MB/sec), so I donated the SSD to the iMac which had a failed 500GB HDD. The SATA II interface in the iMac allows the SSD to push around 250MB/sec max throughput.
 
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