I really like her and think she's quite pretty, and I think just by judging from her outer looks, she would make good foals with the right stallion, but everyone else is right.
I don't believe people should breed their own horses if avoidable, although you don't have to only breed for marketing. My mom is breeding her old mare, for sentimental reasons- but we know everything about her, she has great breeding that we want to keep going, and we have no intention of selling the foal. The foal would become my mom's new horse, and her mare would be retired. Not to mention, my mom knows what she's doing and can easily train the foal, etc.
The issue I see is that you just don't know anything about your mare's genetics.