I have returned my insulated Rossignol jacket (See my review on why, if you wish) and am going with the Gore-tex Pro shell jacket (currently having the following shipped to me: Mountain hardware Vertical, Arcteryx Theta, Sidewinder, and Stingray (We will see who wins out, I will post a thread about my impressions).
My base layer is a Thermasilk with a cap 2 or 3 over it. Up to now, with my insulated jacket, I have never had to use my midlayer fleece (north face TKA 100 microfleece full zip). However, I am sure I would have used it if I only had a shell.
Now I am looking for a thicker mid layer fleece for those colder days when the TKA 100 wont cut it. It probably should be something that has some wind stopper (I think - even though the shells all say they have wind stopper fabric), because when I did go out with the Rossignol Jacket, the only time I felt cold was when the wind really blew (either on the lifts or on the slopes higher up the mountain.) I do generate a lot of body heat but still, sometimes you need help.
I have seen some nice arcteryx soft shells and am also considering the Monkey Man, compressor or nitrous jackets by mountain hardware, but am not tied to either of these companies.
Let me know what you think. Any advice or comment is greatly appreciated.