Many people have tried alternative layouts and stick with them.
I have not seen many anecdotes where people get used to an alternative layout, and then revert to using QWERTY because they find QWERTY more comfortable to use.
Let's not kid ourselves: switching to a new layout takes a lot of effort, so many people quit and revert back to qwerty before they've gotten comfortable with the layout.
Other kinds of bias I'd be concerned about: because learning a new layout takes effort, probably there's emotional investment to avoid having to switch (for those who haven't learned another layout); or probably there's emotional investment for those who have learned, such that they'd be less likely to admit the effort is a waste.
