If you're paying attention even a little bit, you don't need the extra HP from Defender.
Also, Brute is more reliable damage compared to hoping you crit in order to do lots of damage. Sure, when the math is done, all other things held the same, the Desperado is going to output 42% more damage over the base compared to my 25% as a Brute, so it would seem that Desperado is better...
...BUT...
There are a few issues with this assumption.
First, less of my damage is lost to overflow/overkill. If we're both using a weapon that does 20 damage, and we're trying to kill something with 50 hp... I kill it in 2 hits every time, right on the nose. The Desperado does it in 3 most times... but when they crit, they can do it in 1 swing by doing 420 damage... 370 hp more than was necessary. That doesn't save up and make it easier to fight the next thing. That 42% average increase over base that Desperados see truly only applies when you're fighting a block of cheese that would take 100 swings to kill. Much of it is lost, but the math on figuring out the average loss from that 42% is a lot more complicated than I want to try to figure out.
Second, I can use any weapon to do that. Desperados need to find high crit chance weapons to capitalize on their ability... but those weapons do less damage. The best (non-galaxy) weapon for a Desperado is a Wicked Kris at 24-30. If we add the (as we already know, wishful thinking) 42% extra, that brings us up to 34-42, an average of 38 damage. I can instead use the Lava Katana, 55-64, times 1.25 because I'm a Brute makes that 68.75-80, which brings the average to 74.375.
I'll take that 74 damage average over the 38 damage average every day, guys.