Love my KS4's. Can mount 3 on the sled and not be in ridiculous weight territory. It is somewhat established knowledge now that an 'X' configuration works very well. The 3rd axis to complete the magic combo I mount on top of camera, same axis as camera, but tilted up or down at a 45degree angle.
This adds up to the perfect intersection and effect of all 3 gyros. You get the most complementary effect of stabilization, and yet require the least effort to 'break' the inertia in order to actually operate the frame.
Nobody mentions clamping the gyros on the center post? I quickly went away from mounting gyros to bottom of sled and have for many many years clamped the gyros at opposing 'X' positions, to the center post halfway between the gimbal and the bottom of sled.
Works an absolute treat. Hardware is extremely lightweight, minimal and rigid. If your mounting hardware has flex you are defeating the purpose!