By the way,
I overlooked a simple solution that works to some extend:
You can of course manually multiple preload parent beans:
(case: book->page->text)
$texts = R::find('text');
R::preload($texts,array('page'));
$beans = array();
foreach($texts as $t) $beans[] = $t->page;
R::preload($beans,array('book'));
cheers,
Gabor