P4 versus mil dot reticle scopes

Can someone tell me what benefits or downfalls each of these scope reticles have?
How is the P4 recticle used?
That is,What size target is at what range,etc. on the P4 and mil dot recticle scopes,respectively?
I'm pretty sure that an 18" target at 100 yds. on a mil dot scope covers 3 dots for finding the scope range,is it the same on a P4 reticle scope.

I had rather have a plex or a heavy duplex type of crosshair. Better in lower light situations.

Ny poor brain balks at converting mil dots into inches at whatever range. Maybe it works better in meters. I'm with Timbercruiser, i like the duplex. I use the space between the heavy wires as a 6 moa range finder. You can determine this by adjusting the power ring of a variable scope to bracket a 6" bull at 100 yardsand noting what power you are at. 6moa is of more value than the 18" circle of the P4, you can use it to determine the range of coyotes, antelope and elk as well as deer. The bottom heavy wire also make a good aiming point at long range.

get a 4-12x9

www.opticstalk.com will have lots of info for you as well.

what is a 4-12x9???