I tested the shooting and melee stats of 15 basic Quarrellers and Thunderers.
I used an average of ten attacks to find my data.
Shooting average - 4.4 Wounds
Melee average - 1.4 Wounds
Shooting average - 2.5 Wounds
Melee average - 2.4 Wounds
From this data, it appears that Thunderers are a better 15 model shooter than Quarrellers. Quarrellers on the other hand, trade their shooting ability for increased melee capabilities making them a more balanced choice. I am sure people have done tests like this before, but I just wanted to share my results.