I know you don’t think it’s roaring but to share my experience with one with a wind issue. I have an event horse who is a roarer. She scoped clean when I bought her, and then two years later had a sudden paralysis of the right side flap and became a grade 4 roarer overnight.
After my experience with her I would not knowingly purchase one. Not because of the noise, or because it affects her ability to run and jump. She’s competing at preliminary now and will probably have no issues with wind or stamina moving up the levels.
I do however, think it has significantly affected her ability to connect and be through on the flat. Holding her head and neck in that flexed position seems to be something that now causes her stress and panic at the canter. When she is relaxed and quiet at home, it’s not as big a deal, but add in nerves and tension at the show and I think her airway becomes restricted when on the bridle and she has minor come aparts in the dressage because of this.
She’s had a cordodimy which has improved it some but not completely solved the issue.