Enhance "administer permissions" control mechanism

I host multi-sites. I would like to keep the super admin (uid=1) to myself, and create some regular admins for each site. Regular admin would have pretty much all the rights with a few exceptions (php filter, module control etc). One important permission is the "administer permissions". If I grant regular admin "administer permissions", then he/she can grant everything to him/her self. This is what I consider an all-or-nothing permission.

I believe a simple scheme that can fundamentally improve the permission control: the system can implement a simple rule such that a user (regular admin) can change (grant or remove) a permission (e.g. “administer filters”) only if he/she has that permission (“administer filters”) in the first place.

Coupled with this patch http://drupal.org/node/39636 (hide uid=1 from other users), this rule effectively creates a permission "chain" or hierarchy that allows "administer permissions" to be granted to regular admin without worrying about the all-or-nothing effect.

I believe some minor changes in user.admin.inc that can make it work. However, the changes disabled all the check boxes. Can some expert take a look, and tell me what I am missing here? I'd also like to here if my idea is in the right direction.

Thanks in advance!

function user_admin_perm($form_state, $rid = NULL) {
...
        foreach ($role_names as $rid => $name) {
          // Builds arrays for checked boxes for each role
          if (strpos($role_permissions[$rid], $perm .',') !== FALSE) {
            $status[$rid][] = $perm;
          }
          // a user can only change this permission if he has this permission in the first place
          if (user_access($perm)) {
             $disabled[$rid][] = FALSE;
          }
          else {
             $disabled[$rid][] = TRUE;           
          }          
        }
      }
    }
  }

  // Have to build checkboxes here after checkbox arrays are built
  foreach ($role_names as $rid => $name) {
    //disable the checkbox if current user doesn't have this permission
    $form['checkboxes'][$rid] = array('#disabled'=>$disabled[$rid], '#type' => 'checkboxes', '#options' => $options, '#default_value' => isset($status[$rid]) ? $status[$rid] : array());
    $form['role_names'][$rid] = array('#value' => $name, '#tree' => TRUE);
  }
  $form['submit'] = array('#type' => 'submit', '#value' => t('Save permissions'));

This is only for presenting the form, on the form submit, similar checks can put in place to enforce the rule.