What is your opinion on substituting extract for vanilla bean?
totally fine. one teaspoon.
I only really mind doing this when it will MATTER (i.e. vanilla ice cream, vanilla yogurt, vanilla cookies...you see where this is going). If the vanilla is not the star flavor or doesn't need to be strong (caramel is a good example in my opinion), then extract works
Don't hesitate to substitute. As Jessica said, use vanilla bean where it will really shine.