In and of itself, the white color won't affect health or temperament.
Braehead is the only breeder of white German Shepherds that I know well enough to recommend, and I don't know their program real well either. But they put out some nice dogs.
ARCHMX TDCH Pongu the Insane, CD-C, RE, RL1X6, RL2X5, RL3X2 (GSD mix, b. Apr 2010)
Crookytail the Tigerwuff, RL1, ITD (Akita mix, b. Jan 2011)