SD doesn't seem to be as on top of operating system changes as CCC. I don't know how it handles drive recovery partitions, but I do know that since about OS X 10.7 or so, SD has steadily been getting less reliable.
I've been using SD ever since OS 10.9 (Mavericks) came out, and it is definitely reliable (and at times has been a life saver!). It DOES NOT backup/clone the Recovery HD partition, whereas CCC does. But, as I mentioned above, that is not an issue for me, and it is easy to re-create (I provided details above on how to do that).
Also, why do you say "SD has steadily been getting less reliable"? Again, that is certainly not the case for me.
