AFAIK noise of the target only affects detection range. Once the target is detected and locked, it will not be switched, even if more noisy target appears near (or better return for active).
So the point is to prepare target which will be acquired before you can be acquired. Both active and passive torpedo sensors have small range, I guess you won't be able to be quiet enough so the torpedo would ignore you when you get into its acquisition cone. So moving slow has no sense. You just need to arrange it so nixie enters the torpedo's acquisition cone before you.
Anyway I have never successfully used nixie and I'm not even trying any more. Getting away or simply running works.
Smoking them before they can shoot works even better.
As you mentioned, firing back should be part of the evasion !
