Ming-Li
Thanks for taking the time to detail the differences you found between QRecall and Time Machine. I've seen similar discrepancies here, which reinforces my suspicion and Time Machine has its own internal set of exclusion rules, beyond those flagged by the system's "do not backup" list.
I can also appreciate Time Machine's aversion to backing up log files and databases. Without QRecall's block-level de-duplciation, these would quickly consume all of the available backup storage.
Luckily, we don't have that problem.