What do you lose by not having cnc'd heads? What are the benefits? Power? Torque?

50 horsepower. But that's kinda a loaded question.

What's the application ? what's your goal ?

i would say 50 hp with both maybe, 25 hp each if you are running a twin set up. i wouldn't worry to much about that dale unless you are planning on making big hp (above 700 hp). it never hurts, just depends on what you want to spend and what you are trying to accomplish. are you thinking about porting the heads you already have ?

If your only getting 25 hp out of your cnc porting time to find a better head porter!

Depends on what you're comparing the CNC's head to..

540's 700hp dart heads

How much do you think you are going to gain by porting a set of heads? Have you ever had a set done and how much did you pick up on the Dyno, not just what your head guy told you you're gonna make. Btw, not much need to port a set of heads unless you are running blower motors

I would think that a blower engine would be less sensative to the head port as opposed to a NA engine due to the fact that the blower pushes the air in.
I always thought that a NA engine benefitted from optimizing the cylinder heads more than boosted engines.

Actually they both respond equally to the port. Blowers don't push air they compress air. The cylinder head needs to be based off the cubic inch and intended max rpm if it has a blower or not doesn't matter. A blower will help with a poorly combined head/cubic inch/rpm combination but will still benefit more from proper head sizing.