S-Charge and L-Rod are pseudo pets, they cap out at (approximately) 400% damage. Due to the differences in damage modifiers, Scrappers do more damage than Brutes at 400% damage
If you didn't understand the above answer, the simple answer is that scrapper base damage is 50% more than brute base damage. Take damage caps into account and it is easy to see why Scrappers are favored for Elec/SD builds when teaming with kinetics.
There are plenty of threads comparing the actual numbers for the two in various situations. I believe the Scrapper comes out on top for damage in every situation except when the Brute has 100% fury bar, which is only possible just after using the villain alignment power.
Ok, Both brutes and scrappers have High Damage. I have a Elec/Shield Scrapper and an Elec/Sheild Brute. When I use Buildup, against all odds, and 10 medium reds to cap my damage on the scrapper, my sheild charge does around 204 damage. However, when I do the same with my brute, he only does around 134 damage. Both are slotted and enh the exact same way. And yes, that is also with Fury maxed out. What gives?