Seven or more years out from their IPOs, firms with perpetual dual-class stock trade at a significant discount to those with sunset provisions (using median relative valuation)

Dual-class can be beneficial first few years. They provide smooth transition from private to public company. If if there is not a sunset clause, they start performing worse. Performance of Corporate Royalty degrades over time without pressure from other shareholders.

Perpetual Dual-Class Stock: The Case Against Corporate Royalty https://www.sec.gov/news/speech/perpetual-dual-class-stock-c...