If you are doing projects in this size range I doubt you would be using ACAD-E. Especially when you mention P&IDs. Most projects of that size I have worked with, the P&IDs are generated by a combination of the electrical/mechanical people and the majority of the info is extraced from the mechanical "Model" of the process piping (Intergraph's Intelligent P&IDs, aka PDS). My wife is now using a package that runs on top of ACAD for a similar type system as the Intergraph PDS package and so far the term underwhelmed just does not even begin to describe her frustrations.
For the field, cable and conduit schedules for the type of jobs I imagine you are alluding to, the electrical packages that integrate with the PDS type systems would be more to the project needs. ACAD-E is more geared to the machine/equipment level of detail. It will do the conduit, cable and field wiring schedules, but you sound like you are talking large process type jobs where you are more concerened about the power distribution and routing issues (i.e. your duct bank missing that large 48" process pipe that mechanical and structural departments say just can not be moved)
Just my 2 cents,
Darren
