Why are we worried about food vs fuel?
There's only so much we can, and rather less, that we should eat. If there's spare land, why not use it for biofuels?
And in any case we should always produce more food than we need, so that in years with bad weather or disease, there's some spare capacity. I don't think we can leave that to the market, what the market will do in good years with large harvests is massive price drops resulting in farmers going out of business. With no spare capacity, a bad harvest will then catapult prices sufficiently high that some poor people will be priced out of the market and forced to eat less.
Much better for the government to mandate ethanol from corn (or feed some of the corn to cattle) and relax that mandate as required when harvests are poor.
If the resulting average price is great for farmers, but too high for some poor people, I say their food needs to be subsidised.
It's not to say that spare food production capacity is too expensive to maintain and to allow food prices to fall to the point where in an average year the average world citizen has precisely what they need, and in a bad year some go hungry.
If high food prices induce undesirable land changes, the best way to deal with that is to outlaw the land use change. If the country concerned (say Indonesia) does not co-operate, an import duty will do the job, that way the extra corn/vegetable oil will be grown on marginal US/EU land rather than in Indonesia/Brazil.
First generation biofuels can be carbon negative, ie give CO2 emissions reductions greater than 100%. It's just not true that 20% savings are somehow inherent to first generation biofuels and nothing more is reasonably feasible.
Nor is 20% necessarily all that bad when the alternative to increase domestic supply is coal to liquids with 100% greater emissions, similar overall costs and ten times the capital costs even without carbon sequestration.