Mine is a 5-25 and has the P4f. I do not find it too fine. As a matter of fact, I think it is my favorite reticle of all. I dont spend much time on 5X, but the reticle appears perfectly usable to me on that power.
Here is the comparison between the 4-16x50 and the 5-25x56:
4-16x50
FOV @ 100m 7.62m-2.33m
Exit pupil 12.5mm-3.125mm
5-25x56
FOV @ 100m 5.3m-1.5m
Exit pupil 10.95mm-2.28mm
Both have incredible glass and the P4F reticle at .125 MOA thick is a great addition to the scope. The 4x and 5x bottom ends of these scopes constrict FOV somewhat (the 4-16x at around 4.8 and the 5-25 at around 7.8) but the reticle vertical and horizontal outside stadia work well for picking up the crosshair at lower power.
As far as brightness goes, tough to tell a difference between the two. I've included exit pupil sizes above for relative light delivery to the pupil on min & max magnification. Both have stellar optical quality.