Rukia's Shikai just plain owns, I put it in a class with the other "your pretty well screwed if it happens to you" powers.

it's not always about who has more 'power' in fights.

Take Yumichika, he's probobly not as strong as Hisagi...8th squad Vice...I think thats his name, but he put him on the floor and came out unscathed. Rukia's Shikai has a power like that or Tousen's or Aizens, it doesn't really matter who you are or how much power you can spit out your ass, you would need extremely specific skills to beat them.

To beat Yumichika, maybe have way more power than he can suck, (which does require power from the ass...)
To beat Tousen, be Ken, or piss Tousen off so he becomes an idiot and doesn't cut your head off immediately
To beat Aizen........................join him, since you don't have too much choice in the matter.

In Rukia's case, maybe you can stay out of the circle, though i'm sure another dance throws the circle at you. But basically if your caught by surprise then you die, assuming you can't survive insta-freezing.

That said, IF Deroi needs to survive, then it's very possible that spirit power can melt ice.