The fuel lines should be as ethanol-compatible as they can be: they've been designing sleds around running E10 for over a decade. That doesn't change the fact that alcohol attracts moisture, and moisture is hard on everything in the fuel system. You should be ok for how long a typical sled lasts, especially if you add some fuel treatment (Sta-Bil 360 looks good, but there are several good ones to limit damage from ethanol). That said, I'd never run a sled on E10 that's not fresh, and eth-free is a better choice under all circumstances and will give you the longest life on the fuel system.
If I'm understanding what @RBalazs is saying, the issue is that pure gasoline isn't electrically conductive enough to limit static buildup when fueling. I'm pretty certain that it's not an issue on cars because the fueling receptacle is normally metal (or grounded somehow), where a sled has a plastic gas tank. That makes me wonder if a metal collar under the fuel cap - grounded to the chassis - would prevent this. That said, I would think keeping the nozzle fully in the tank until the fuel reaches it should prevent any sparking - or if it did, there'd probably be too little oxygen to ignite the fumes. Usually, a gas tank has too rich a mixture to ignite anyway - you could drop a match into a full gas tank and it'll just go out; it's a nearly empty tank that's most likely to go boom. Regardless, it just seems like too small a possibility to worry about or be worth running E10 for. Unless you're a lawyer, or like keeping them employed...
