Here's my 2 cents.
If your good at getting around in 3D autoCAD and are a pretty good piping designer, than Cadworx is the way to go. Good program with great support. Easy to maintain specs and things like that. If your doing plant design with multiple piping specs it is very useful. Also get the Isogen package it works great to. Produces some good looking ISO's if you ask me.
Incase any Coade people are reading this.
I do have several complaints (some people would call it a wish list) about Cadworx. I have more than this but they are all minor.
Their equipment modeler is horrible. I just use their piping components to build up my equipment and standard Acad commands and it works pretty well.
If they added one component to their spec builder system, you could build any piping spec in 30 minutes instead of the 4 hours it was taking me. I suggested it to them 2 years ago haven't seen it added yet.
They now have a steel package which is pretty good.
Overall I give the package an A-
I miss it (changed jobs 6 months ago), in a different industry now and we are using Solidworks.