What is your opinion on running a leg drop mag pouch for four 5.56 magazines as an infantryman?

I personally hate leg-drop anything, whether it is for mag pouches or a holster. If you are looking to clear some pouches off your carrier, look at getting a battle belt. There is a wide spectrum of belts out there, but I would stay away from the type with a padded piece with molle weave that fits over a belt... the material will start to sag down from the weight. Make sure you get one with molle actually on the belt - I like the Blackhawk Padded Patrol Belt. Get some taco mag pouches for your weak side, mount your pistol on the strong side, and you'll be all set.

The bottom line about any kit set up is what is practical for you. Meaning knowing where everything is without having to look for it. The idea of a leg drop anything is not something I would recommend, yea you may look cool to the POG's (Fobbits) who have never done anything but when you're running and gunning you'll realize that you've made a mistake. Try different variations of how your kit is set and move it around until you can operate smoothly without to much interference.

If you don't want to/can't mount stuff on your vest, I'd suggest a MOLLE belt. Trying to pull mags out of a leg mag pouch is just going to be a pain because it will ride up every time you try to pull one out. Unless you have it tourniquet tight. I, personally, have been using a belt and I'm glad that I invested in one.