I am also heavily interested in both of these styles. In a way I guess you could say Bak Mei could be used for Wing Chung, since its angles of attack are made to break the centerline.
White Tiger is very fast and explosive from what I've seen, and uses a hunched back, as well as sinking/risking movements. Both aren't as watered-down as alot of the other kung fu styles because they are more rare, and slightly well guarded. Bak Mei has a reputation of still being taught as a very efficient, deadly fighting form, From what I've seen there is alot of Pheonix fists attacks to vital points. There is alot of chi gong practice, and intense physical form practice as well.
White Tiger, in form, practice, is some of the fastest punches I've ever seen. I don't know much about the styles, but they are advandced, and focus alot on the internal aspects of striking.
"Truth is found when mind reaches the point of absolute nothingness, but in reality this nothingness is everything possibly imaginable, in this truth the mind is in absolute stillness, the absence of thought is truth"