Probably not really worth it. It's a minor increase, the random health on zeds does mean it's roughly as "useful" as the damage difference actually is, but the bullet damage difference isn't the whole story. Just to understand the actual damage effects, you'd have to hop on a test world and shoot at a few zeds..
Things like decap chance are also tied to the damage, more damage => higher chance, so even in there the high damage does help.
I guess the real question is, how are your horde nights?
Are you being flooded with zeds, or just waiting for the next group => do you actually need the DPS?
Is your ammo box overflowing or permanently empty? Is there even a need for crafting the ammo in the first place? ..
I tend to run a surplus of all ammo types unless I'm sporting an M60 and am having an untypically wasteful day. I don't really need to make any 9mm => what I make, might as well be of a different type as you don't really get the specials from anywhere. If I'm making a special type of ammo myself, I'm always making AP, mainly for the multitarget function, but the boost against demos helps too...