Nah man it shouldn't eat through your lines that would be if your probably left it for a long time without use,just have to empty the tank run 98 and leave it. The only thing that ive found is that you need to get supporting mods that can handle the alcohol content otherwise you shouldn't have any problems with the fuel line, that's probably the least of your problems. I'd be more worried about the consistency of your fuel because it could throw out your tune and depending on how aggressive the tune was it could go pop.
I don't think they meant that your octane will drop but they meant your mileage will drop, since E85 has a lower energy density meaning it burns more to produce the same as regular petrol.
http://www.injectordynamics.com/AlcoholArticle.html
Have read at this site might be worthwhile INJECTOR DYNAMICS wrote it.
They are still fixing the site so i cant dig up the thread its under Forced Induction