If you're expecting ambush drive to be your swiss army knife all purpose PK tool... it isn't ever going to be.

It's a useful niche ability, much like strangle, offhand disarm, spores, worldbind, entwine, or a hundred others. If you tried to spam any of these things in every PK, you would get your ass handed to you; however, in the right situation, they're valuable.

Ambush drive is like that, and trying to sell it short here isn't going to convince me it needs to be better unless you can make a much stronger case than you have. It's really only going to convince me that you need to be better.