I would give anything to get a blue roan just once in my lifetime haha.
I've tried, and tried, and tried some more to no avail.
I thought I got lucky last winter when I bred my strawberry roan mare to my solid black stud. The colt dropped on the ground and he was as blue as he could be, with a small tint of gray. Long story short, now at 7 months he is as chestnut/bay as it gets, with no hope for blue roan. Im sure he will develop fully into one of those two as he gets a little older, but its still hard to tell so far. He's going to be a good one, so color doesnt bother me, but I thought I got lucky on that one.