This Buetler formula, with its high dilution, wouldn't be what I'd consider "fine grain" in the traditional sense; there's only going to be about 4 grams of sulfite in a liter of final working solution, less than a gram of metol. In fact, if anything, this reminds me more of a low-contrast developer you'd use to get pictorial results out of a microfilm, without any attempt to optimize film speed. I'd guess times will run long, too.

I'd expect to see considerable speed loss in continuous agitation compared to long-interval intermittent agitation with a much longer process.