Yoshi still uses Babolat VS natural gut in the mains.
During Australian Open, he was trying out a silver poly string for his crosses, most likely Luxilon Alu power
Recently he won the Columbus Challenger and was using Yonex Poly Tour Pro in the Crosses
I think its a good move for him to try out new polys. His regular setup was VS in mains with Yonex poly tour spin in the crosses (Blue-5 sided Poly)
Interesting to see him switch from a shaped poly to a smooth round poly. I'm guessing he wanted more consistency and to be able to flatten out the balls a little easier. Spin is def not an issue for him.
He had a great win with his new string setup against Jenson Brooksby