I wasn't clear on my first comment; not that EFI will be dodgy only that it hasn't been available to try out.
That said, you'd have to get some major improvement in mileage to make the dollar return a consideration (if it's dollars and not consumption that you're keying upon).
For instance, if you're lucky enough to put 20K on the bike you'd have to up the current average mileage to over 60mpg to save $400 and IMO it's unlikely EFI will show that marked an improvement.
