Can s/p be effective without zerker gears?
It’ll work, just remember that when you’re evading or your enemy is missing due to blind/weakness, tough/vit are doing nothing for you. People invest so heavily into offensive stats because they have means other than defensive stats to mitigate damage.
If you don’t mind losing ~40% of your damage, sure.
As Tulisin said, there’s plenty of ways to survive without having to rely on stats.
If you want to maintain decent damage but get a bit more survivability you can use a mix of valk and zerker.
It could work, but your dps output would be much less than Zerker gear. If you’re looking for something in the middle, you could always use Knight gear. That’s what I use on my Venomous Aura S/P build. However Knight is really too dangerous to use on a Thief unless you’re getting constant healing (like I am through Leeching Venoms and crit proc heals).