Interesting, I didn't know. But with micros() I think that it is more precise.
Actually this week I did some tests with the oscilloscope because I was curious to see how precise and fast can be the loop generating a square wave: Pulse output timing accuracy? - #22 by gromit1
Using micros the error seems to be below 4 us.
I tested also the loop in 'free run' and it takes about 3.2 us to switch. The overhead of the few instructions, interrupts and other MCU entertainments.