OK, I'll jump on.

In the early days of 8-speed and 9-speed drivetrains broken left side spokes were an epidemic. The reason was that the amount of dishing that was required, even with 130 mm dropouts, along with careless machine wheelbuilding resulted in a bad combination. Since that time wheelbuilding has improved and off center rims have also greatly helped to reduce this issue. Using a run-of-the-mill wheel from that era with 126 mm dropouts would have been suicide.

Bottom line, I might try using a wheel that I built myself with a 9-speed freehub body with 126 OLD spacing, ALONG WITH AN OFF CENTER RIM, on a personal bike but I wouldn't risk it for a customer bike.