Razor,
For now I am trying the two nalgene thing because it is my comfort zone. Being a former USMC Grunt type one each I always carried two canteens etc. I am going to begin experimenting a bit tomorrow on the range. If I were to dump one of the nalgene pouches I am a bit concerned about the balance of the rig. But it's all a matter of experimentation.
Reaper,
I go with the hard sided water bottles on my second line because they are a bit more rugged than a bladder. Getting in and out of vehicles a lot / under fire etc I'd rather have something a bit tougher.
Please keep the suggestions coming! I am sure this will get changed around as I test it out under a bit of pressure on the range. Check and test... Check and test...
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UPDATE: NDD I conducted some dry fire drills at home and I relocated the pistol magazine pouches. I will try this new location live fire and see if it works. If not I'll keep experimenting.
Thanks again.