Which one should I choose? Does P3D benefit from the four extra hyper-threading cores?

I understand P3D does benefit from the extra virtual cores, in terms of faster scenery loading. But you must have the right affinity mask setting.

 

Best place for advice is the P3D forum.

Yes, as Martin says. the HT version can provide a marginally smoother ride. However, with P3Dv2 an affinity mask will be required with hyperthreading enabled. AffinityMask=254 is a recommended starting point for 8 Logical processors running P3Dv2 or FSX Boxed.

 

However those with Steam Edition FSX should note that FSX-SE handles best use of the HT enabled cores itself, and so an AM is ignored by FSX-SE.