[SerraAva]

The problem is that a t-stand might be rated for 200lbs vertically, not horizontally. If you have a 50lbs moving head or two swaying back and forth, it might tip over because it isn't rated for 100lbs horizontally (absolute worse case scenario). Moving mirrors have much less horizontal force as its only the mirror moving and not the whole head. This is why putting a moving head on a t-stand is dangerous. If its a stick of truss with two stands, the amount of horizontal force is spread between at least two stands and the truss, not just the stand its self now.

I would agree with putting the 250s on stands/truss and 575s on the floor/cases. The 575s are more then bright enough to punch through 250s at that angle depending on color. I have also used 575s in the past at the side of the stage as side light to great effect with 250 mirrors on a truss in the back. You could also look into CMY fixtures, so color matching isn't as much a problem.