"wtforms_components provides better HTML5 compatible type handling than WTForms at the moment."

[DuncanBetts]

I can see this assertion was made in or before Nov 2013, here.

Would you agree that this statement is still true? Here's the WTForms changelog.

Thanks :) have just discovered WTForms Alchemy too, it looks like it might be able to handle the work I've spent the last hours doing (figuring out how to set up a form correctly with layers of nested forms).