Metaphys is a high risk high return kind of deck. If it fails to open the key cards and bricks (which is easy for that deck, considering how many high level monster it runs), it's dead.
I'd say Darklord is the more consistent deck, and therefore would have higher chance to win against Metaphys.
Only if you play free-to-play Metaphys.
Optimal version does not brick, and Grit helps you survive, after you start your engines run there is almost nothing your opponent can do anymore