Your assessment of the KEF vs the Wilson's is interesting, but if your KEF's weren't producing enough bass then the KEF's would sound thin and bright. Personally I think the Kef's image better and are more coherent than the Wilson's.
The 205.2 aren't known for producing Wilson level bass, the 207.2 are known for their deep bass response.
There are many good speaker cable recommendations depending on price range. Looking at your system I would upgrade both your interconnects and speaker cables. The Nordost Quttrofill cable doesn't sound anywhere as good as the new Norse series cables which are much more transparent.
It depends on the tuning of the system, the MAC amp is warm the ARC is not, the modified Primare is hard to know what that sound like. So it will come down to tuning and the taste of what the sound you want is.
If you want great clarity go with Norodst Frey interconnects and Speaker Cable. Great bang for the buck range. More transparent is the Tyr which is very similar to Valhalla.
The Nordost have a huge sound stage as well. If you want more warmth look to the new Cardas series of cabling. I would stay away from Network cables with a Mac amp, way too muffled sounding.
If you want a warm sound with a very organic feel go with Kubala Sosna Emotion series.
You should get rid of the vibrapods they make equipment sound soft.