It seems each manufacturer has there own preference for digital connections. Perhaps it is in the design of the DAC or transport that makes one connection inherently better than another in certain gear. EAD always used to recommend AT&T glass. Ed Meitner, noted digital designer, recommends AT&T because it breaks the ground between components. The late Howard Mandel of Altis Audio also recommended AT&T, and all his high end stuff came with it standard. So is it a good connection? Absolutely. But we are talking about AT&T, not toslink, which is an inferior connection. Perhaps toslink is the connection Mgl123 is talking about when he says that "high end stuff doesn't even offer glass". I think you are referring to AT&T by your reference to "ST", which is another designation for it. Not only does some high end gear come with AT&T, but Theta had there own dedicated optical transmission system called "laser link", I believe.
I experimented with ST cables and connections with every DAC or transport I had that supported it. I found the ST connection to be dead quiet, very black background, lots of detail, but somewhat sterile. That was in the system I had at that time. It's sure worth experimenting with if your digital gear supports that connection.