I hear (and know for a fact) that pole piece vented woofers and subs have more air radiating (a hole in the back of the magnet) and thus better voice coil cooling. But if a speaker is magnetically shielded, how can it benefit from this ? (the whole purpose being that the back of the magnet is open, so that the air can evacuate).
For this reason I'm trying to find some without but it's quite hard. Anybody know of manufacturers that don't shield their speakers?
Thats why in my search for bookshelf speakers, I am hesitating to get shielded ones. Is there any logic to my reasoning? Am I missing out something?

Any comments appreciated.