It's a hard call. Remember in Malifaux you don't pick your list until after you know what faction your opponent is playing and after you know your strategy. The situation might determine whether or not you need the third Gamin. Rasputina does burn through a lot of soul stones, so I think in most cases you will be better off without the third Gamin.
For what it's worth, I would also consider picking up the Sabertooth Cerebus. I would use him in place of the Ice Golem to bring a little bit more speed to your list. So it would look like this:
Rasputina
Essence of Power (2 SS)
Silent One (6 SS)
Silent One (6 SS)
Ice Gamin (4 SS)
Ice Gamin (4 SS)
Ice Gamin (4 SS)
Sabertooth Cerebus (8 SS)
5 SS Pool
But then again, I would use the Blessed of December in place of the Cerebus, once the Blessed comes out.
Hope it helps!
(Edited for clarity.)