Benefits > drawbacks.
Although, the best thing to do is buy yourself a ethanol sensor (from any GM or Ford Flexfuel truck made in the last 10 years) and a standalone that will adjust your fuel/timing tables vs the freq input of the ethanol sensor - or if you need an analog value, use Zeitronix's ECA. Then you can throw pump gas in it if you need to, and you get a fuel temp sensor (for varying fuel density with temp/etc) in the mix for free.
And of course, if you need help with any of that, we're here
