An issue was raised in this thread:
Describing the problem where:
causes MyObject to be coerced to a String before being coerced to a Boolean. For some objects this may be an expensive operation, and the common case (how often is the Entity you are editing on a page actually null?)
Adding an explicit Object -> Boolean coercion will remove the need for the Object -> String coercion.
A Number -> Boolean coercion is also required to prevent Integer -> Boolean from choosing the Object -> Boolean as a match (currently it goes Integer -> Long -> Boolean)
At this point the only known issue is that any POJO that depends on the fact that returning "false" from toString will cause the Object -> String -> Boolean to return false will be broken. This seems like an unlikely case and can be worked around by providing a specific TypeCoercion for that object.