Going Sunni -> Hindu -> Sikh has the benefit you won't need to spawn any rebels as long as 50% of your provinces are already Hindu
You can accept the Hindu Zealots' demands as soon as you place a missionary
Most of my land is still Sunni, as I ate most of Persia and Afghanistan from the Timurids. But duly noted, once I make more progress into India proper.
That said, I may *want* them to convert things, so that my religious unity isn't like... 0, and I don't have to spam missionaries everywhere.