I've been asked this by a few couples and have been chosen by them for the very reason that I have a LOT of experience shooting interacial couples. I have quite an extensive portfoilio of many different ethnic combinations
(black/white/Indian/Hispanic/Asian) and feel really comfortable not only with the shooting aspect but more importantly, the post processing.
What's quite interesting to me is that wedding photographers - of all types of photographers - should have the most experience handling the contrast difference because frankly, we shoot it every single weekend - her White Dress-his Black Tux!
;o) Can't get more tonal contrast than that. If their images show good detail of a brides dress and the groom's tux, they should be capable - you would think.
Also, if you find someone's work you like and still aren't sure, just do an enagement session with them and address your concerens to them. Work on ways to make both of you feel comfortable.
I'm skilled to handle my equipment but a lot of it has to do with that and the editing. Full blast flash is a killer for that contrast - they need to know how to skillfully fill flash without overpowering and it means dialing it back to a
more natural level.