I went through a few sacks of Chevallier. From the farmer's perspective it's far worse than Maris Otter. It was the choice British variety from about 1820 to 1880. It is very tall, so very susceptible to wind and rain damage, gives poor yields, prone to disease, all sorts of trouble. It was not grown much after 1880 (superseded by the Plumage Archer varieties, ancestors of many modern barleys including MO) and not at all after WW1 until it was recently retrieved from a seed bank by Crisp. So you can see why it is very expensive. It is also hard to brew with. It does not make a very friable malt, needs a relatively long and intensive mash program, and still yields relatively poorly in the brewhouse. But, oh! the beer it makes. No more delicious, aromatic, mouth filling, foamy, etc. beer can be made. (The passing of Chevallier was one major factor in the adoption of crystal and other specialty malts British beers, an attempt to make up for the lack of flavor and body in beers made with newer barleys.) But it's not going to be worth the cost or risk to very many farmers or commercial brewers. But homebrewers with no economic constraints may enjoy experimenting with it.