Cool Gilda - I love brachys so its always nice to see another one.
Shakkai - S. Gratrix is a very good breeder with other brachys or brachy hybrids. As is typical of most paph types though (brachy, complex, multis, parvis) the breeding potential drops quite a bit if you breed between groups. That being said, when a cross does take, some of the coolest and most novel flowers are produced - the Rolfei types, etc. An example I believe you saw recently was my Color My World 'Shocker' flower (S. Gratrix x Winston Churchill) Anyway, if you have a good S. Gratrix, by all means use it...it has produced some wonderful crosses and will produce many more.