I did upgrade my hdd and I am positive your CFW did not change. 😏
However, if you upgrade your hdd, I think you will lose your CFW as I may have lost my CFW when I upgraded my ps3. Furthermore, when I changed mine out, I had all my CFW's ready to start from scratch. No big deal. Don't have to worry about having to reflash anything though. Ps3 will still be jailbroke.