ohhhh is THAT why my sweeps were being so weird in 3D?!? After some panicking: I thought I just accidentally added worldspace/playerpos to the Displacement (viewrot*10m) due to re-using the var for debug_draw.DrawArrow()… but maybe I imagined that, and it was just euler-lock practice 
edit! haha yup! All along, It was just because I enabled physics in that playground lol!
BTW I tried with both versions of SpatialMath and same issue, I guess they will make a GetViewRotation() for LUF that will prob work in the physics playground later.