I've got a player who zips around the battlefield using her Wizard school ability (I'm not quite sure whether it is the Conjuration school dimensional steps ability or the Teleportation subschool shift ability, but I think the latter). She insists that this works with Dimensional Agility but I'm not so sure. Any opinions? This is for PFS.
Dimensional Steps takes a standard action, so probably isn't what the player is using that's bothering you. Shift works as Dimension Door so Dimensional Agility should apply to it. Though that's really only useful if you Shift in the middle of an action. The wizard could easily move then cast a spell and then Shift without needing Dimensional Agility at all. I also suppose the wizard could instead be an exploiter, and have access to the Arcanist's Dimensional Slide ability.
The end point is that there are quite a few ways for a wizard to zip around a battlefield. This is mostly only an issue on big maps, where the long distances can be meaningful.
Yes, definitely expect table variance, because "as if using DD" is not the "Ability to (...) cast dimension door". Indeed, RAW, it is a crystal clear "no", because Shift is a supernatural ability, and thus you don't "cast" anything (which is what the feats require). Dimensional Steps is an SLA, but it doesn't reference DD at all.