I tried lots of strings and this is by far my favorite! Very powerful but also warm sound for viola. The strings also can stay quite good long period enough for me. for half year of intense using is not a problem. I used 6 sets of Peter Infeld and absolutely satisfied.
cons:
Since they are steel core strings , it take some time to play in and warm up the strings, usually I change at least 3 -7 days before when I really need the best sound from the strings. So maybe this is not a best solution right before concert or audition to use it.
But overall, I can only recommend it!
in my opinion, Peter Infeld are well balanced, not as super powerful as Spirecore C, G string , but just perfect tension for me. and not as light or simple to dig in to the string like vision Solo. But that is also perfect for me.