I can tell you I've soloed up through Ulgo on my assassin. My gear choice is a little unconventional and I have augmented most of the pieces, but it seems to work ok. When I got all of my Battle Master gear I was a DPS assassin, so I am in stalker gear, but have since switched to tank spec. As a result, I can put up decent enough damage to take down the bosses before rage timers, but the self-heals and armor boosts from tank spec keep me alive.