I think you would probably be safe with Apple's migration assistant, but cloning will definitely work.
I highly recommend using CCC for bootable backups in general, and it is really easy to use. Although, I am still using an older version, but I doubt it has gotten more complex.
It seems like each version I'd getting more simple and easy to use.
One thing though, I would make backup if your HDD, make sure it works externally first, then update your internal HDD to High Sierra to get the firmware update.
After installing a SSD, I tried going from 10.10 to 10.13 on a Mid 2011 iMac, but was unable to install past 10.12 due to not having some firmware updated.
I couldn't update the firmware on the SSD, from my research, it had to be an Apple OEM drive.
I swapped everything back, updated the OS to High Sierra on the failing drive, and swapped everything again, and was able to install a fresh OS on the internal SSD.
BTW, the SSD with be a huge upgrade to the Mid 2011.