unless packaging a vacuum booster is a problem, I personally wouldn't run hydroboost.
Why? The steering system on an offroad rig has enough demands on it already.. if you don't have a hydro-assist ram, then it's working hard just to steer. if you DO have a ram, the pump is having to send fluid to fill a hydraulic ram.. I don't want to put additional stress on the already taxed pump.
Vacuum boosters work just fine and provide plenty of assist power.
Both of them suck if you lose the engine after the first pump or 2, so that's a wash.
The PS pumps from a hydroboost setup are good to run for your steering, though..