The question is a bit complex than a simple reading of these files. Mac OS sandboxing allows dynamic extension of the sandbox, which would not be reflected in the profile (I'd bet Safari does more of this than Blink though). Also, as you mentioned, it's relevant to look at what's factored into separate processes, and how those processes are sandboxed. Safari's Network process has been networked since 2013, so I don't think you can count Chrome's ongoing work to do so as a Chrome advantage.
If you add these things up, the difference in practical effectiveness is not as wide as one might think.
If you add these things up, the difference in practical effectiveness is not as wide as one might think.