I have a ShockStop stem, 11cm. Yes, the effect is more noticeable when in the hoods. There's more leverage that way for the shock to be felt. It seems odd you are placing so much need for shock absorption when on the tops. I ride the tops when on fairly smooth pavement/no need for shock absorption. When you start hitting gravel, bouncy, or sketchy areas, most people move to the drops, don't they? I read over and over riding in the drops is recommended for control in sketchy portions. And that's when the shockstem come more into play. Or the hoods, as i do. that's when you need the shock absorption effect, no? Maybe you should reconsider your handlebar tape or gloves.
I have my RedShift ShockStop stem set with 2 elastomers for riders from 185-205lbs. I weigh 205. I also have a steel gravel bike, a Norco Search XR 105, with 650b wheels and 47 wide tires tubeless at around 40psi. Again, I'm not looking for the full shock absorption effect when i'm riding on the tops. When it starts getting gnarly, i move to the hoods. Full effect in that position.
I'm really liking my new stem and the shock absorption if offers when i need it. And i don't even notice it when climbing out of the saddle.
eric/fresno, ca.