I use to own a Gamma 6500 stringer and never had any issues with snapping poly, even the infamous SPPP 1.18 strings. When I switched to a Babolat Star 5, I snapped it doing the mains. Tried again and after the racquet was fully strung and removed off the stringer, the string snapped while sitting around after 5 minutes. I was shocked and never used SPPP again.
Never snapped Kirschbaum Proline 2, MSV Focus Hex, MSV Co-Focus or Solinco strings on the Star 5.