ID is a very nice skill for just messing around, though at high lvl, it's not
really all that important. It is quite fun however to run through oasis or
WC and kill SG or HG. And this is made mostly possible through use of ID. I
have soloed a SG w/o using it before, but it was way to close to actually
depend on being able to kill them regularly. With using it, I have soloed SG
and only lost half my hps, not even using mend. Though it's not very
reliable, I can normally count on it working at least once or twice in a
fight of the sort mentioned above.

Kanja
50 monk
Rodcet Nife