Biofuel researcher here: The nice thing about switchgrass is that it's a much hardier plant, meaning that you can get it to grow on marginal lands, which means land that wouldn't otherwise be used for crops.
Getting people to grow anything for biofuels is a bit of a double-edged sword, as you want the feedstock to be as cheap as possible, but you also want it to be profitable for the farmers to actually produce so that you can get enough of the biomass. If you improve the yield of viable biomass from the plants that'll go part of the way to solving this.
If the stuff is efficient enough as a source for gasoline replacement generation to be worth making gasoline from, subsidies shouldn't be necessary to ensure a sufficient stock. If it requires subsidies, that indicates a big problem with that plan. Unless the main goal is to reduce foreign oil independence. But I'm skeptical that that goal is remotely feasible with biofuels without making serious compromises in food-generating land. We should be spending this effort and funding on improving battery tech and creating business models that make electric vehicles appealing (swappable leased batteries, for example), as well as improving nuclear power tech to feed those vehicles.
EDIT: Algae seems like it could be promising, assuming we could find a way to mass farm it without disturbing ocean food cycles.
Getting people to grow anything for biofuels is a bit of a double-edged sword, as you want the feedstock to be as cheap as possible, but you also want it to be profitable for the farmers to actually produce so that you can get enough of the biomass. If you improve the yield of viable biomass from the plants that'll go part of the way to solving this.