Rob -- I am about as conversant in Wax as you are. In fact, I had not even noticed any reference to Photoshop. I saw the plug-in for Adobe Premiere and other programs, but not Photoshop, so I can't help you there...
As for benefits from the program vis-a-vis what VS can or cannot do, I said it all when I just mentioned:
That includes rotoscoping, a particle generator and 3D titling. Best of all, it seems to work with Vista.
Great for those of us who don't have Graphics Lab or have found that Cool 3D/Production Studio doesn't work under Vista!
In effect rotoscoping allows you to 'follow a highlighted head' by allow you, on a simplisitic level, to insert a highlight in a moving video which lets the highlight follow the highligted area of video across and around a screen. A great tool in its own right.
The particle generator allows you to do, say, titles which explode into tiny particles or dissipate in a mist of particles etc. And 3D titling (including particle effects) is something that Cool 3D/Production Studio does well but very slowly. But it doesn't work in Vista. So that is why I am pleased about Wax appearing to work with Vista. And there are a ton of other things in Wax I haven't even explored yet.