In an HP DV7, there is a 32GB mSATA card acting a cache to the 7200rpm hard drive. I'm going to reconfigure the lap top and add a real 128GB SSD as a boot drive. Question is which is faster the existing 7200 rpm drive with the 32gb mSATA cache or disable the mSATA and replace the existing drive with a new 7200 Hybrid drive?
While I haven't tested it, my educated guess is - neither. You'll get the big boost from booting from SSD. Having cache on your data drive or not having cache on your data drive won't make much of a difference, except in power draw.
And you won't care once you see how fast things are with an SSD system drive!