I have a limb saver on my 300win mag savage that was 7.5#s and metal kickplate.. Ya, after a few shots, no one wanted to shoot it. I put one on it and now it's fine for 10 shots or so.
I also put a blackhawk shock absorbing stock on my mossberg 535. I think that it makes a huge defference, and after firing it, i can see that its moving about .5 inch when firing the 3" hornady coyote shells.