The infamous Schilke 51D. Every eupher knows about it. Almost all of them have tried it, or play on it. However, I consistently hear accounts of the 51D being too small (in cup width), tight, or otherwise less desirable. Why is more attention not paid to the 52D, which is (in theory) totally identical, save for a slightly larger cup width? One could even special order a 53D, even wider than the 52D.
Additionally, the 52E2 seems like something worth trying if one wasn't happy with a 51D.
Is it just lack of marketing or general knowledge that the 52D, and other less-common Schilke sizes are almost unheard of?