use sysctl hw.usb.no_shutdown_wait=1 to shut down can make some damage ?

[yoxter]

I´ve installed FreeBSD 9.1RC3 with ZFS on a USB external hard driver.

I am using :

sysctl hw.usb.no_shutdown_wait=1
poweroff

To turn off my computer.

can it make some damage to my external hard driver ?

PD : I am using this way to turn off my computer cause i have this bung