Hybrid drives like those Seagate makes take the most used 4 gigs of stuff that is accessed lots. It can make a performance difference when starting the system and some programs, but is not like having a SSD.
It is not bad, but if you need the space, the 750 is a better option.
Another thing you can do is if the laptop has a DVD drive, you can in many cases get a hard drive holder(Or SSD
) to place in that spot then put the DVD external(if you do not use it much).
EDIT, yeah if it is an M-SATA cache, you can upgrade it