Again comparing the different plugins and solutions, this one still comes as my best choice
However, there seems to be one feature that is offered with Gravity form + custom Types (not f=ree, though), that is the ability to populate custom fields options (for ex for a select box) with taxonomy values.
It is an advantage when you want to enable users to perform a search based on these options, as I guess it will be much faster query using taxonomy than custom fields options. Yet, putting it as a custom field option makes it easier for the editor.
So... that si another suggestion to look at!
Thanks for the great job!