Something you have to remember is that when u throw an instrument like this into a mix, it may sound TOO real, which then dramatically increases a listeners expectations of a playing performance. Personnally i wouldn't mess with this, cause ur almost always going to get the best performances from people who are good at playing the real instruments eg. that Ari woman who is phenominal. Even to have a violin player a fraction as good playing on one of your tracks would probably be sufficient. I prefer to sketch out ruff melodies or chords as guides, and then get people who play the real thing to interpret that, and then throw their magic on it. To learn all the playing nuances of an instrument takes alot of time, time i don't have. Another thing i've found with some of the super realistic libraries is that they sound too clean and pristine, and to make them work you have to spend a shitload of time dirtying them up to make them sound hip hop, which after that point, u may as well have started with an average sample. Don't get me wrong though, these types of samples have their place for sure, like in soundtracks/soundscapes, classical etc, but i'm not sure they work for hip hop. Breaking rules is important i guess too!