Do you have "in flight adjust"? I tried two "UHS 9P" spinners(one for 2 blade, one for 3 blade) on a medium with "in flight adjust" and while it worked in general there were problems with the back plate warping. The 9P is extra long to accommodate the adjustment motor so any change was really obvious as wobbling at the tip. The "back" plate goes forward of the adjustment motor(at least that was the design when I was going through this). As you torque the six prop bolts the fiberglass warped even with extra wide washers and threw the spinner off center. Did it work...? yes, but not ideal and could have been a problem down the line. I imagine a squash plate would help, but that meant more weight up front and even longer prop bolts. Perhaps the ground adjust version allows the back plate to be placed behind the hub effectively creating a squash plate effect. I ended up changing to a Kiev for moment of inertia and weight reasons anyways so don't know how the condition would contribute to longevity. It also kinda scared me that the IVO is pretty specific on torque and relies on the knurled plates to grip the blades. Throw some fiberglass into the sandwich and you could have some torque changes with compression. Maybe I was over worried, but food for thought.