Would that (gently used) cherry of a 1970 Toyota Corolla fetch a higher price if its eight-track player has been upgraded to Apple CarPlay? There’s a corollary for the advice business: Might deal-hungry private equity firms be willing to pay more for RIAs that have their own exchange-traded funds? A company that provides third-party services to help businesses launch ETFs says yes. But there’s some nuance to that, and adding new funds certainly isn’t the right move for everyone. “Anybody buying an ETF b ...