You will only get a performance increase in common files such as boot time.
A good SSD+HDD config will beat a single SSHD. SSHDs are generally budget oriented or for laptops to take less space.
For data, the SSHD will read files that you have put on there an use a lot very quickly, files that are not used much will be read at the same speed as a usual HDD.
Thanks for the prompt reply, what I meant was do I go SSD + HDD or SSD + SSHD. I'm also using Ramdisk to speed things up.