Shield Bash vs Shield Impact

i just got awaken and i notice the new shield stun will replace my shield bash. so basicly i have to trade

shield bash : 3 sec reuse (base) 2 sec stun + cancel target

for

shield impact : 10 sec reuse (base) 1 sec stun + some dmg

so i dont need the dmg i want cc. i was wondering if i enchant my shield bash +15 does still have good chance to land ? cuz i dont wanna replace it with this stupid stun, but i dont have choise if chance to land become very low cuz of level penalty.

 

it will be useless after some lvls, you want to keep it for pvp.

but how higher the lvl between the other player and your shield base is how lower the change it will it. even when you make it +30 i say you will have a low change on players with lvl 90+

 

enchating this skill to +15 (max) will make it 85 lvl with very high chance to land (90%) vs same level champ. i cant find info how much it drop with the lvl difference.