Unfortunately not, as it is primarily my conclusion based reading about it and engaging with proponents. Maybe I should write a blog post or something.

In short, I think it is outdated because it is a material consumption and utilization tax applied relatively regressively.

Henry George lived in the 1800s when economic value creation primarily was primarily through agricultural and industrial utilization of natural resources (farming, mining, manufacturing). Since then, the value creation in industrialized countries have largely shifted to service and knowledge economies (finance, medicine, entertainment, technology, arbitrage, and IP). Service and knowledge economies are much more detached from natural resources consumption. As and example, a banker might make a million dollar trade consuming little more than the electricity and a PC, whereas a farmer needs hundreds of acres, Water, tractors, fuel, and fertilizer.

One might think that the tax burden would get passed along from the primary users of natural recourses to the end consumers, and this is may be true to a degree. However, differences in consumption is much more flat between individuals than income or wealth. Your Warren Buffets of the world might have an income 100,000 X higher than the average person, but they dont consume 100,000X more material goods like food, water, housing, ect.