Your work flow and mine are pretty much the same, P6 for posing, Silo and Hex for modeling, Vue 6 Pro Studio for rendering.

However, I think you've missed the boat a little by not giving C5 a try at least. I find I'm going to C6, now, more often then Vue, unless I'm doing a super hdri image.  IMHO Vue does have the superior render engine, but, Vue is at heart what it is a landscape renderer.  You know those jagged edges you can get on a Poser Character when rendering that will not go away not matter your AA settings, won't happen in C5 or C6. On the other hand, the implimentation of hdri in C5 or C6 leaves something to be desired, though it is there.

C6 does not required the additional resources of Poser to allow you to adjust a pose, on the other hand, if you use multiple runtimes as I do, C6 cannot find .objs, etc, till you tell it where they are.

My suggestion to you would be take some time to play with C5, if you like it, you'll love C6.