I may just be exasperated at trying to get routing to work at all, but there's a large part of me that says don't bother, although they sell it, it's not a complete product. The demos all work great and all, but the moment you try doing something yourself that's not in the carefully crafted demo, you may as well be considered a beta-tester.
As for described feature content, I do think that just the routing package would do what you want, it claims to be able to do all you asked for. The electrical package is geared towards PLC racks.
By now Matthew will no doubt have been able to look at the website.
The following link gives a nice overview about the differences between the different SW's
Don't use the electrical part myself. The tubing hardly ever gets used by us. We bought SW premium just because we wanted to draw piping in 3D. It's not been easy. They make it look simple and the basic things are but if you want to draw something more then a skid and with types of pipes of your chosing, instead of what they offer straight out of the box, you'll have a steep learning curve ahead.
Main thing to keep in mind is that because of the specialized nature of what you want to draw/design you'll have to take time to adjust to the program and don't expect to be able to do everything within a month as well as having to find work arounds so as to be able to do things that the program can't yet handle. E.g. until recently Routing didn't support HVAC piping nor cable tray routing.
Having said that, considering that we have even drawn the piping for complete Bio Gas energy plants with it. Including several kilometers underground pipes, I think it's safe to say that you shouldn't be afraid to take a closer look.
Main thing is to decide what you want to do with it, if it's possible to do it and if it's worth the price and effort for you to have the tools that it offers.