Seconding this - my horse has Storm Cat three generations back on his dam side. He also has Cormorant three generations back through his sire. Most of our issues arise from him being too smart for his own good as opposed to him being particularly hot 
We x-rayed the majority of his body back in March because he’s been having issues with holding his lead, especially to the left, but all we learned from the films is that there’s nothing physically wrong with him (his vertebral spacings are perfect), he’s just all legs and needs to get stronger now that he’s finally done with the growing up part.
OP, whichever horse you decide to move forward with, (as many people have already said here) I wouldn’t assume physical issues just because of a particular sire a few generations back. I’d also add that a very good friend of mine has a Jump Start gelding that she adores. He’s had some issues health-wise but they have everything to do with poor care under prior connections and nothing to do with his breeding, and I know she’d love to have another Jump Start baby if she could afford to keep two horses consistently.
