yes, snippet=1 is here for some time

(or at least until the new architecture

)
adding an extra param to output all variables as json is probably doable in the template itself. You just need to dump the contents of the array
$smarty->_tpl_vars as a json element (i.e. json_encode?). Only hassle is in some pages we also send in some objects, which u'll need to skip. We also send in the config and session object which you should definitely not send out
lobo