sounds fine as a secondary drive. but it really depends on how you want to use it.
the files on the SSD will be faster, but if you have applicaations that make heavy repeated use of a small subset of their files putting those applications files on the SSHD makes sense.
moving the OS to the SSHG is not going tomake the OS faster, and unless you have a need for the space that the OS consumes on the SSD for some other purpose, leaving the OS on the SSD id probably the best way to go.