I do not like the way Promise-E wants to do things.
I prefer my own layout arrangements for the documentation, etc.
I never understood how the were able to get as popular as they became with what is basically a simple add-on.
I have seen several people have trouble with it's learning curve, but I din't think that it is real bad myself.
ACAD-E is great, but a little pricey.
AutoCAD LT is probably more then enough for most people.
Actually, I prefer a drawing board, but that is another fight.
I have used Unigraphics, and more complicated programs for control cabinets, switchgear, harnesses, and routing. Mostly on Locomotives and mining and construction equipment (6-10 high tires). They make for some impressive 3-D drawings, but major overkill for most.