i am not sure, but i think it forms a sexlink, i could be completly wrong though. I remember reading about sex links, and i thought if you cross a solid to a stripes/lace the females will have the fathers base color and the males will have the mothers base color, it was an old article, i coul dbe wrong.
White is a masking gene. If the white bird has gold under there you get one thing. Silver another. Columbian another. Barred another yet = barred.
In this case your rocks would be " a box of chocolates." You never know what you get until you try LOL
As long as any bird used is a Rock, you still get dual purpose rock type. You just can get some wild stuff going on, especially if you cross subsequent generations.
What you can't generate is partridge but that's about it.
It can be tons of fun if you aren't concerned about showing.
As long as you sell off or cull smaller, poorer birds and poor layers you can go with a whole EXPLOSION of colors, that are and aren't standard colors.
If you use a BR roo over anything, all chicks will have some barring. BR hens make great sexlinks because the males will be barred and females probably mostly solid colors--I've had that experience with several different breed roos over BR hens.