need to use $elt->{att'}->{$att} for a value though

Actually $elt->att( $att) is what you want, to use an accessor instead of assuming that the attributes are in a hash (they are) and will always be (there is no guarantee about that anywhere in the docs). (end of the rant ;--)

is this the same as the method 'att_to_field'

Yes it is! And I had completely forgotten about this method. Thanks for reminding me of its existence. That will teach me to write more methods than can fit in my head.