I don't really understand "losing one's temper" and the whole threat-display escalation thing (well, I can see it in theory, but I don't know it from the inside), so I find it difficult to play characters who do it, but I try it occasionally. I find Bad Temper goes well with Stubborn: I'm fed up arguing about this now, so I'm going to shout at you.
In the
Travelleresque free trader game I ran a few years ago (in 4e but prior to GURPS Ultra-Tech), one of the PCs had Berserk. This served him particularly well when he got himself into a judicial duel which he started to lose; the recording of his frenzied attack, on behalf of someone he didn't even know very well, got him a small fan club, which once he was out of hospital he quite appreciated.