The biggest reason would be that the fuel system needs to flow about 30% for all conditions. Most vehicles require bigger pumps, injectors, and even lines. It isn't as big of a concern for most modern cars, but some components do not react well with the more corrosive ethanol. Special hoses, seals, lines, injectors, pumps, and even senders are needed. Some cars are more compatible, older ones tend not to be.
Higher compression than in gas form is desirable to take advantage of the fuels octane and to offset the lower energy content. The majority of starting and drivability issues is totally dependent on the tune, but even OEM's have struggled with this one at times. Given access to enough parameters, it should not be an issue.
The stock tuning will not be optimized at all to run it. Timing, injection quantity, and even target A/F ratios will be completely different for any given condition. The fuel system seems ok, at least for more minor modifications. FI would need some changes.