A previous utility that I worked for built several 115 kV lines using 959 ACSS-TW. These were all either radial lines to distribution substations or were normally-open loops.
Prior to switching over to the ACSS-TW, we used 795 ACSR as our standard transmission conductor but determined that the ACSS would greatly increase our ampacity in an emergency (when we would happily accept additional line losses). The new conductor used essentially the same structure design as the ACSR, so the bottom line cost differential wasn't really all that much - the difference was limited to the cost of the conductor itself and of hardware that could handle higher temperatures.