Regardless, a critical hit from ID
is not guaranteed. And without an ID crit, ID won't pull significantly ahead of a standard MNK rotation. A Bootshine crit will always do more than an ID non-crit, and a Bootshine crit
is guaranteed.
Impulse Drive is not useless, but it is very risky. Between crit chance, the possibility of missing the rear attack bonus (hate shift, mob moving), and working in other MNK skills on the fly, you are walking a tightrope - and there's no significant payoff for success.