I know this reply is super late for the discussion but here is my 2 cents worth of opinion (again).
For elegant and high end items where they are worn for special occasions, vitreous enamel works fine. Will it crack or break at some time? Depends on how the person wearing it, treats the jewelry. but sometimes accidents happen and repairs will be needed.
Now to take my wife’s jewelry as an example, being from India, she wears a lot of bangles. Her nice ones handed down in her family will sometimes have a crack or two, but overall are in great shape and look great even being very old. Close to a century for one of them.
But everyday wear jewelry, most of what she has is either paint, or colored epoxy in the recessed areas. Only upon close examination can you tell the difference.
So it really depends on how it is treated. I have used both in my jewelry depending on the possible usage.