gistfile1.txt

		$m=$this;
        $m->thumb=$m
            ->leftJoin('filestore_file','filestore_file_id')
           ->leftJoin('filestore_image.original_file_id',null,'left')
           ->leftJoin('filestore_file','thumb_file_id','left');
            ;
        $m->vol=$m->thumb->leftJoin('filestore_volume',null,'left');


        $m->addExpression('thumb',function($m,$s){
            return $s->expr(
                'COALESCE(
                        concat('.
                            $m->vol->fieldExpr('dirname').
                            ',"/",'.
                            $m->thumb->fieldExpr('filename').
                        ')
                , "templates/default/images/profile.jpg") ');
        })->visible(true);

for the single user, you can use this:

$path = $user->ref('filestore_file_id')->getPath();

(this shows the full image)

$path = $user->ref('filestore_file_id')->ref('thumb_file_id')->getPath();