If you try and use a field of type float or Float with DataForm, it appears to work, but does not commit properly. Changing to Double works fine. The problem is with setProperty in EntityBase. If the default DataFormDecimalEditor is used, then it tries to call (eg) setValue(float) with data of type Double, throws the exception, catches it silently and carries on - this is very bad!!!!! It makes it look like everything is working, but in fact it fails to commit.
See attached screenshots.