Having never shot wedding with a D100, I might not be able to help much.
I can however tell you that the blinking highlight mode is the default display mode on my D100 when I shoot landscape. I find it to be a great tool that is faster to interpretate than the histogram.
Overall though, I personnally find that the D100's exposure is not super accurate in many circumstances. I do never trust the camera without checking for blow out highlights. This is no problem at all when you shoot landscape, but it might be a problem for wedding or PJ work. From what I read, other DSLR don't perform much better though.
Best regards,
Bernard