I'm not sure it would be more efficient. Starches from corn or potatoes is pretty cheap, and if this synthetic meat can use it more efficiently (I wouldn't be surprised at at least an order of magnitude or two) compared to an animal in the wild, that's relatively little feedstock per pound of meat compared to what we pay now.
And using the same kind of biotech we use to break down cellulose to make cellulosic ethanol, we might be able to create feedstock for this meat from agricultural waste or fast-growing grasses.
This is precisely this type of reasoning that I fear:
* Starches from corn or potatoes is pretty cheap (money, heavily affected by federal subsidies).
* Synthetic meat can use it more efficiently (the engineer in me wants to say "energy", but depending on the context it may mean higher utility margins, or lower labor costs, or what not).
* Same kind of biotech [as] cellulosic ethanol. I am not familiar with the state of the art on this field, but (corn) ethanol companies just engages in arbitrage tricks to make a bundle on yuppie's eco-guilt and government's largesse. Both the economy and the environment would be better of if people just shut up and directly burnt the diesel used in machinery used to rise and transport the corn used as raw inputs to make the ethanol.
Not that this particular argument is wrong, just that I do not have the facts and would like to see them discussed without all the hype!
And using the same kind of biotech we use to break down cellulose to make cellulosic ethanol, we might be able to create feedstock for this meat from agricultural waste or fast-growing grasses.