For the benefit of those with enquiring minds who haven't spotted what I would have thought was actually pretty obvious, there is a worthwhile benefit from being able to line up the pusher along the axis you need the chuck to move. Basically you can score a hole in one, most times: Measure runout once, correct once.
With the conventional Set-Tru, Grip-Tru, or Ajust-Tru setup, you either have to scribble down the runout and the phase angle relative to the pusher screws and do some trig, or (more usual) do multiple trial and error moves, because the correction is shared variably among a pair of pusher screws.
What I tend to do is use one pusher only, to nudge the body sideways until the runout DOES line up with the pair of screws at right angles to the one I initially picked. Then it's a one-shot correction.
Fusker: I wouldn't be too hesitant about taking heavy cuts.
Provided your three clamping screws are of suitable size, they will create enough friction grip to keep the chuck body from moving, unless you have a crunch-up, that is, in which case you'll have more pressing worries than a bit of runout!
It's a widely used rule of thumb that a high tensile bolt will create a similar friction grip to the allowable load in shear. (ie the force to shear the bolt, reduced by a suitable safety factor)
My comments about the chuck weight were just on the topic of whether a heavy chuck body would move only along the desired straight-line axis, or describe a falling trajectory like a bullet during adjustment, which it seemed to me might defeat the 'once only' objective. As I understand the design, there's nothing constraining it to a straight line, although I guess if the ring were machined with an oval rather than a round bore for the chuck, perhaps this could be achieved?
I'm sorry you struck such an ill-informed and closed-minded response, but there's a "bit of it about" since that unfortunate outbreak in Mexico City a while back.
