SLs alone aren’t enough to remove the whiff factor.
I have played extensively with wh frpg 2e and troika! (which has an opposed skill check combat resolution system).
It is simple mathematics that an opposed system reduces whiffiness, and in my opinion, sufficiently so. Allow me to demonstrate.
In warhammer 2e, at lower level, your WS tended to be poor - say 33%. Your attack had thus roughly 2/3 chance of missing
from the get go - and then your foe had a chance (not great) of blocking/parrying (say 33% again), so only 22% of your hits landed. That
IS whiffy.
(I'll note that aim and charge helped a bit for this, but whatever)
If you were a powerful warrior (say WS 66%) vs a low skilled for (ws 33% for the parry), your chance of landing that blow was 44%, which is better, but not amazing. Vs an equally skilled foe, you were back to a 22% chance of hitting.
(meanwhile, the unskilled fighter only has a 11% chance of hitting the skilled warrior)
But if you have an opposed check, this whiffiness vanishes. If your foe is equally good, you have 50% chance of hitting said foe! And it doesn't matter if it's two drunken peasants or 2 highly skilled duelists!
Hitting 50% of the time
is not whiffy.
If it's the skilled fighter vs the unskilled one, the skilled fighter's blows will land 66% of the time (if my math is correct), so again, a clear improvement. However, the low skilled warrior's chance of hitting remains 11%.
So the problem was solved. What does advantage add to the situation?