What would you recommend instead?
You need archery at least, so that's two slots. I think Sharpshooter is more useful than steady aim in solo runs, so I run sharpshooter, and the third passive usually alternates between Brooding/Steady Aim/Night Stalker.
Generally, I'll use Tactical Advantage to gain the ability to actually escape from champ mobs/find the next check point, and then Cull the Weak for bosses (unless they spawn mobs, in which case I don't use Rapid Fire + Web Shot like I would otherwise).
Speaking of soloing specifically.
A dh that doesn't use Ss. Now I've seen it all. That and preparation are requirements in hell+.
Edit: unless you're not saying that you don't use it. Can't tell.
I don't use it. If the math isn't on my side and it really does add a ton of additional damage, let me know. The 15% guaranteed additional damage that Cull the Weak brings against slowed enemies seems more substantial to me.
I just solo'd SK in Inferno (it's as far as I've gotten). I can't take on champion mobs at all in Inferno, but normal mobs go down so quickly that I'm not too worried about Crit building up every second.