Harrier carries 300 25mm. Hornet carries 500(?) 20mm. So 330 25mm isn't so terrible. Apparently the 4 barrel design is more accurate than the 5 barrel GAU12. Also, I think the 25mm round is significantly heavier than the 20mm so as long as you don't suck at shooting, I'd say 330 is pretty deadly.
Also everybody is going to get ridiculous about it, but full stealth aircraft are meant to fight BVR. You aren't launching with the intent of going to the merge and if you do, that's what missiles are for. Say what you want about "tried it once and got shwacked" but that was almost 50 years ago. We did learn our lessons and I doubt we'll let the turning fight skill set die, but if we can do it this way with better reliability and survivability, then why not?