We do not currently use draft animal power on our farm, but we are members of the DAP Network, and we really respect the wisdom of the DAP farmers. Their sustainable farming practices are gentle on the land and help preserve rare draft horse and oxen breeds. (We do use animal power in the sense that 6 months of the year our sheep harvest their own feed, saving us considerable fuel in harvesting and moving hay. We have been considering oxen for our farm in the future.)
A study in the Midwest found that horse farmers make more money per acre and have a higher quality of life than tractor farmers, primarily through lower costs and taking rest breaks when the animals also need rest. (Total income was lower because they generally work fewer acres.)
The DAP Field Days is a trade show of sorts, a old fashioned country fair focused on animal power.
Consider the Draft Animal Power Field Days Indiegogo Campaign