That's the way I thought it should wor (and found snippets like this on various site)
{foreach from=$product.features item=feature}
{$feature.name} ==> works
{$feature.value} ==> works
{$feature.id_feature} ==> works
{$feature.id_feature_value} ==> returns nothing...
{/foreach}
Hope it explains better what I try to get.... Thinks, I'm pretty just thinking in a wrong way and got stuck in a timetunnel 😉