It comes to me that helper has some weaknesses:
1) It is hard to test . No easy way to write test code for it.
(or Just i didn’t know?)
2) Not easy to reuse it on other controller/view/model.
it looks like to that putting the helper code into a model (a
fully helper model , or a mixed model) is good practice.
However i agree that some html intensive code still sites best
in helper .