"I do not know what you mean by "sweat""
"modern hoses are made from very advanced compounds (EDPM) etc. and are virtually unafected by oil products -- they also can take acids/ strong bases."
Not true, at least with the compounds used in oem MB hoses. This is from experience. Sweating is when the hoses become porous, and coolant beads on the outside surface. It appears as 'sweat', and I have only seen it with MBs. The oil seems to cause the rubber to break down rapidly at high temperature, because the problem only occured with ours in the area forward of the front firewall - not in the space between the two, nor inside the passenger compartment.
'91 MB 190E 2.3
'08 RAV4 Ltd 3.5
'83 Lazy Daze m'home 5.7