I bought an OCZ SSD to use a cache drive for photoediting with Lightroom. This was a waste of money.
The constant caching of thumbnails eventually worn out the SPEED of the SSD. That is, the SSD still reliably hold data, but the wear-levling algorithm now causes monumental fragmentation of the files. The thumbnail files are constantly getting 'blown' to bits by the SSD wear-leveling: into 10-100's of segments. As such, the files are now (after 6 months) read as fast as from a good HDD. I've finally moved on to using a RAMDISK as a cache drive. Admittedly, the available size is considerably smaller than an SSD, but much, much faster and not prone to permanent fragmentation.