So just back from Govt' sponsored tourism.....
#1 Failure... that is a nice rig... but I must ask the advantage of folding irons vs. a red dot @ 45 (which is how I have been doing it)
#2 Caliber is important, but environments drive your situations, and situations drive your tactics. When I think of tactics I think of who is trying to apply what and where. The who and where I see as the big factors in this discussion. Distances have been the focus of the discussion and I'd agree that they are the #1 factor in caliber selection. Smaller is easier closer IMO.
Another factor has to be looked at that is often overlooked in this discussion. Flexibility
I find 7.62x51 is much more flexible than 5.56 as it has a greater variance in configuration. I see these wars we've been fighting as not winding down, but spinning up. With the Russians and by proxy the Chinese developing new body armor designed to protect against 5.56, the current stop gap is 7.62x51. Handl Defense has been in talks with some people who worked on the last caseless project for HK and I sat in on the conversation. I am convinced that Small Arms has to change and the brass cartridge, impact primer, and copper case bullet is where the change starts.
But for now; if I want to punch steel/plate with a 180gr AP, I want a hollow point boat tail 175gr sub MOA round, 110 or 130 gr defensive round for soft targets, or even API, I can do this all with 7.62x51. These rounds are also available in platforms that can be used in a CQC environment or in a DMR setup. Yes this can be done with 5.56, but not to the same effect. When it comes to terminal ballistics its not even close.
#3 the other part of this discussion is who. I think 5.56 was selected for many reasons like when zeroed @ 25m the POA-POI is very close to the same as 200m. This means without discussing ballistics to draftees, you would have the greatest possible effective hits with the least amount of training. Zero it and point to shoot, for what is considered pretty much max range for a nug to shoot out to.
For the most part the admin chick who weighs a 100lb is not going to wield the SCAR H or HK 417 very effectively. Many of the limp wristed, fat, xbox drones we are going to end up drafting once a city or two gets hit with weaponized bubonic plague ISIS is working on, are not going fair well with it either. So maximize the effects of 5.56 but leave the killers a real option. Right now the only one that can do it all is 7.62x51