Michael,
Showstoppers were TCL and ADP compatibility in a sense that ad_form didn't work hamoniously with plain HTML inputs declared in the ADP file. Matching ad_form -form elements (i.e. TCL file) with html input (ADP files) caused wether duplicity and overwriting conflicts or unawareness by ad_form.
Plus, ad_form worflows didn't work as expected (i.e. edit_request, validate, on_submit, etc)
As per your example, I can see now that the reason could be because I've tried b), replacing