It is really just what the individual finds does best for him or her.
So, experiment and seek your best solution.
I know this sounds a bit trite yet it is the truth.
I've found the ghost better for long range precision but the notch is quicker to acquire a target. I use the notch, I'm not going to be picking off a mugger at 30 meters.
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Moscow rule #7: Lull your opposition with a false sense of complacency.