Hmm. This sounds like it could be a tough one and would require some fairly intensive getting down and dirty with code.
I think you'd need to use something like:
http://wordpress.org/extend/plugins/custom-field-template/
But you'd need to get into the code base and modify how it displays.
Assuming user1 is set with an access level of say 5 in role manager, and power-user1 is level 6 then you'd be able to use something like:
<?php
global $userdata;
get_currentuserinfo();
$level = $userdata->user_level;
if ($level = 5) {
// Show one custom field template
} elseif ($level >= 6){
// Show extended custom field template
}
?>
This plugin is really quite nice - but I'd say if you asked the plugin creator whether something like this would be possible he might have a better idea - it could even be something he'd see fit to add to the plugin (eg being able to set each template as assignable to a user level).