Context: I bought the strings for a small German viola circa 1900 - 381mm back/360mm vibrating string length. I acquired the 25.5 kg tension strings to replace some very old Obligatos. So old, new strings were always going to be better; consequently I can't really compare these Tomastik with the Pirastros.
At the time of writing this review, the strings have been on for two weeks and seen action in a concert including Shostakovich 5. The strings settled in very quickly, performing evenly across the board and I was very happy with their response in the concert. They were easy to play. The C is sonorous, the G rich and the D sweet. Of the four, the carbon steel A might is possibly the one I might question, but I'm not unhappy with it and it sang out in the viola section's famous first movement solo. Overall, I wouldn't disagree with the descriptive graphs given by Thomastik on the back of the box.
Conclusion: Nice quality strings that working well on my small viola. Thumbs up.