Backstabber is still a must unless you for some reason want to lonewolf him. Hell, you cant really go wrong with backstabber on anyone who does melee.
It's a 100% wasted perk on a bro with 95 melee attack. It's a skill for bros with low melee attack on early game. Recover, relenteless and even quick hands are far better perks for viper.
Plain wrong, good sir and here's why.
First of all, you arent going to have mass 95 melee attack bros unless you severely neglect some other important attribute, esp on ironman. With a mass two-hander tin can army, you can do just fine with 85 ish melee attack & backstabber and pump spare points into m def or fatique. This allows most of my late game meleers to have over 45 m def - I dont remember when was the last time anyone died in close combat. And hitting aint a problem either.
Second, you dont take into consideration that the enemy also has skills & cause you injuries & use the terrain to make your m attack plummet. Overwhelm being just one example. It's in these situations that backstabber shines. Esp good on backline polearm users, when you absolutely need that reap to hit and roll heads.
And third, if you play ironman, that midgame backstabber makes things so much easier when most of your bros have middling melee attack, but good potential to become demigod tier smashingtons.
