even if it has been done, why not repeating it if you would like to have the plants and espcially if you have two good parent plants, with threads you would like to have in the hybrid? I would say, go for it...
check RHS if C. violacea has been crossed with any other Brassavola, and try to find pictures to see the result you could expect from your cross... and then decided whether going for it or not!
There is now way to know for sure that any cross will come out viable. I'm with Ramon, just give it a try. Brassavola and Cattleya are very closely related genera, my bet would be that it would work if both parents are diploid.
Wow Kavanaru that is amazing i think i might try a maxima to i think they both could be good crosses i'm going to go for it . The violacea and cordata are both opening now. i am going to wait a day or two so i can get some pictures of both fully open.
Waiting until they are nice and open is always a good idea for maximum chances of setting a capsule. Too early and the pollen interferes with the flower maturing, too late and the flower may drop before fertilization takes place. Plus we like photos.