FluoroSilicone fuel sump o-rings

[A2022]

I have had Viton o-rings installed since December 2012, but they are no longer sealing effectively and have struggled to seal well in very cold weather. After researching the topic, it appears that fluorosilicone would be a superior material for this application. Has anyone here had experience switching to fluorosilicone, and would you recommend it as a long-term fix?

Buna color = black (original as shipped)
Viton color = brown
Fluorosilicone color = blue