Should I upgrade Purist Audio Design Proteus Rev B from fluid filled to Ferox?

Advice sought. My Purist Audio Design Proteus Rev B speaker cables are slowly losing their precious fluids (Dr. Strangelove joke). The company says they will upgrade to ferox for about $400 plus shipping charges They say almost everything will improve. Does anyone with experience with these cables have an opinion on whether ferox is better than fluid? My speakers are PSB Imagine T3s.

Thanks for your help.