If you want a black mask DDB why not just get a bull mastiff? Not being sarcastic-seriously asking your thoughts.
I know BM's and DDB's are similar...but dont they also have some main differences? Not just in looks, but in personality? What you are asking is purely about looks and not about temperament or general personality. I suppose if someone was looking for a mastiff based purely on looks and a black mask was something they HAD to have, they should go with a BM or an EM as a black masked DDB is pretty rare.
But I'd think (hope) most people are also looking for a certain personality in their dog...and the DDB is very attractive in that way...well you know...you have one
but say someone wants the DDB personality...and also loves the black mask... then I guess they'd find themselves a DDB with a black mask.
Kind of like I think an Isabella colored dogue is gorgeous and would jump at the chance to own one. But just because I like that color doesn't mean I want a different breed that is more commonly colored that way...I'd still want a DDB cause they're awesome.