So, in the ARG, the Undine race got a nice little feat called Hydraulic Trip, which allows them to use the Hydraulic Push to perform not just bull rushes, but also disarms, trips, and certain dirty tricks (blinding and dazzling, specifically). This naturally makes the spell a lot more versatile, and I think it's neat.
So, which class can make best use of this ability? The spell is available to druids, magi, sorcerers, and wizards. It's also one of the first ki powers a Qinggong Monk can learn. I personally think that a Monk with the Qinggong and Maneuver Master archetypes (and a vow or two to boost their ki pool) can do very well with this enhanced Hydraulic Push.
But is there something I'm missing?
So... I guess that makes Monks the best users of Hydraulic Maneuver, then?
It's like you're a water bender at that point. Sounds like a fun concept.
Make it a Drunken Master for infinite Ki and go to town.