Yes, Add PhilC's toolbox to my list as well, plus colorcurvature's figure mixer. I use M4/K4, V4/K4, D3/Matt a LOT! And the clothing converting utility that comes with it is what MAKES it useful!

If you include Poser's built-in features, then the one that I simply cannot do without is the Morph Brush and all it's wonderful permutations.I absolutely do not have any mesh issues anymore... I use it to make bends look more natural, to make clothes really FIT... to make hair actually shape to heads... to fake contact physics between characters... all sorts of things. It also is what makes the cloth room truly useful... it cleans up all the bend crinkles in the dynamic meshes and makes those clothing items appear real.

Yes. I'm a big fan.