Cable manufacturers will make a specific type of cable, but when you have to string several different types into an umbilical they have no idea on what they are doing. For exmaple, when you're mixing coax with data cable and power cable into a robotic sheething using a PVC waterproofing outer layer that is meant to be used in the harshest of conditions, I highly doubt that they can give you details of a specific requirement. "...On a far wider scale and far longer term than you could hope to do on your own". Yes, this is true, but the larger their scale the less detail oriented they become. Don't expect a one size fits all. On top of that, try getting a hold of their engineering staff to question them and see what answers you get. They will not be able to tell you how long the cable will last. If they're smart they'll ask whats the ID of the PVC tubing being used. They'll come up with a sample of the size of cable. They'll test for fit. They'll ask how long is the PVC tubing and how will one go about pulling the cable. They will not be able to judge life expectancy. They wont even know how the PVC tubing will work with the cabling. I doubt that they will have the time to suggest proper cabling for your needs because of the amount of detail involved.