It's not a rosy picture at all.
It would even be viable if the total amount of carbon generated by the farming, processing and transportation of biofuels without including burning but subtracting the carbon taken from the air by plant growth, was a net positive by itself, as long as the excess was less than the corresponding total for fossil fuel production, including all the carbon involved in its production.
I accept the validity of what you said about land use in the sister thread, but I don't think you've established that this criterion isn't true (and making the much weaker claim above suggests that you aren't able to).
I also believe that many types of impact on the environment (for example what you mentioned about topsoil and water quality) should be treated with much lower priority than the greenhouse effect. If biofuels, or some other strategy for reducing emissions such as solar or wind power generation has a devastating but localized impact on some ecosystems, it might be worth it to forestall the wider effects of global warming. This is a matter of opinion though, and I do not live in an area which could be sacrificial in this sense.
No, I'm saying it's of dubious climate benefit (compared to fossil fuels), and has outsized environmental externalities besides.
https://www.reuters.com/business/environment/us-corn-based-e...
Not to mention that your goal posts are so incredibly, unbelievably far from where the industry started. Corn-based ethanol was pitched as a bridge fuel to get us to cellulosic, and was supposed to have real, tangible environmental benefits. This also doesn't touch on the fact that the subsidies involved have distorted several climate-relevant markets, most importantly the consumer market for inefficient vehicles in the US. When gas prices go up, demand for inefficient vehicles goes down - US biofuels are giving inefficient cars a huge boost.
> I also believe that many types of impact on the environment (for example what you mentioned about topsoil and water quality) should be treated with much lower priority than the greenhouse effect.
In some cases I agree - see mining of minerals for batteries. It just happens to turn out that if you look at the whole system, biofuels are a scam from a climate perspective, as well as an environmental disaster in their own right.
> This is a matter of opinion though, and I do not live in an area which could be sacrificial in this sense.
I live in Iowa, one of the most modified ecosystems on the planet, and ground zero for biofuels.