Yes, I am still using P4 (despite having both P5 and P6).  Why?  Because the current versions simply cannot match P4 in terms of ease of use, render speed and overall performance.  I can live without the face room, dynamic cloth. ray tracing, etc.  If P7 is going to be as bloated and clunky as P5/P6 then I will stick with P4.  Hopefully, e-Frontier does a better job in moving the Poser platform forward.