50% chance off major bosses with 5NV (and you should have 5 NV stacks anyway for the bosses). So, in that regard, it doesn't sound bad.
But given these new recipes won't be any different than random rare drops, then there's no reason to give a fark about them.
50% at what mp? I've killed the Butcher with 5NV at least 20 times now. I can't be THAT unlucky.