mxmkr makes a good point
I have found that no matter what string sound I use, realism mostly comes from playing that particular sound in a manner that sounds, well, real. In general, single note high note lines played properly can sound pretty real. It is mostly in the articulation that the realism gest lost. With real strings, each note, each phrase, each passage has its own articulation. Articulations change from note to note, register to register. This is where synth sounds fall short. That is also why a Wendy Carlos can, in my opinion, approximate real strings. Is is in the detail of articulation, of changing sounds, colors and articulations throughout any phrase. This is labor intensive and requires extensive experimentation and a huge library of string sounds. So, in the end, I am sure that there are plenty of Top 40 records with Roland Strings but this is usually a simple line above the chording to open up the track. Sure there are some more intricate parts but more than likely, if the string lines were that important and the producer or arranger was competent and the budget sufficiently large, real string players were used.
Face it, you cannot make a machine into a man nor a man into a machine and you should not try. Each have ther place. Trying for absolute realism with a synth is in a way ridiculous. Instead, if real strings are that important, get them. I am sure the string players could use the work.