I like to keep my mags on my off hand side and front of my vest. Dump pouch is on off hand side easy to reach without reaching behind me. Everything else kind of rotates depending on where I'm playing.
Do you run a plate carrier? I run a gbbr so mags are heavy. while running they would move all over the place! something that really helps is making plates for your JPC. you can make them very easily out of a childrens swim kick board. -i know it sounds funny, but it really works! everything will stay in one place making it easy to run. not sure if you deal with that, but thought id throw it out there.