ORIGINAL: MJD
Latex rubber slowly degrades over time. It is floppy, kinks and squishes easily and costs more than silicone, and is not usually sitting on the LHS shelf in rolls for $1 - $1.50/foot. It's good for pressure bladders and shut off timers and needs occasional replacement but no matter for those apps. It is also good for bungees, histarts, and tourniquets.
Polyu does indeed embrittle.
Polyethylene is very stable and chemically resistant. Do you have some flexible PE tubing that would work well on a fuel system? If so then use it.
Silicone has many desirable properties for glow fuel, and nothing else I've ever used works better and costs the same or less so why bother IMHO.
MJD
So, essentially, fuel lines are consumables when flying glow fueled models. Like glow plugs, propellers and fuel, they are consumed over time and they need periodic replacement. There is no such thing as life time lasting fuel line. <G>
Ed Cregger