I think you are making a responsible and informed decision. That right there is why many people get shot down for wanting to breed their mare. One old thread in particular sticks in my mind. This person had a mare than was older but you couldn't ride her because she wasn't sound for some unknown reason, possibly navicular. And even when she was sound, she would buck when you tried to ride her. She was an okay looking mare but nothing that screamed (or even whispered) "breed me". The mare was a rescue and had no papers and no accomplishments to speak of, even being saddle broke. Those are the types of people that make me cringe.
You know horses and know enough to make a good decision about what to breed your mare to and if you want to take the risk when the time comes. If I owned your mare and was looking to breed, I would probably look for performance lines because they would cross well with your mare and they are the most versatile. As for re-sale value if it should come to that. It is so much easier to place a horse that has some good solid training, which I know the baby will end up with, than one that has been a pasture mustang for 3 years and never seen a halter. I have 2 babies right now that are mutts and though I do plan to forever keep at least one of them, the other would not be sold without solid training because solid training raises the chances of a solid home. But then again, I am simply stating facts that you already know all too well.
I think if you want to breed your mare, that's awesome and you will choose the right stally for her. Did I mention that I used to have 2 sons of Watch Joe Jack and I absolutely adore the line? If you do breed her and end up needing a place to re-home the foal, look toward TX.