just stop, the weight difference is immaterial to try and argue otherwise is beyond childish. It's like arguing whether half a snickers bar or 3/4 snickers bar is too much before bed.
none of us are humping 100lb rucks up the mountains where ounces equal pounds.
I can see we're not going to agree here, but I'll keep asking questions anyways. Now maybe we're saying or thinking different things here. So I'll concede that I agree there is a slew of dudes who obsess over a few ounces of rail weight without changing anything else and act like its going to save their back, or bitch about quad rails for some dumb reason.
But thats NOT what I'm talking about. I'm talking about the idea that you can optimize gear and weapons to increase performance, endurance, stamina, etc....this is, of course, regardless of strength or whether or not you "hump 100lbs rucks around the mountains", which I've done plenty of. In fact, humping that much weight is one of the reasons I adopt this mindset. It does not just apply to heavy weight, but to anything.
The weight difference of anything is not immaterial. Unless you actually believe that there is no limit to a difference in weight that matters? Would you realistically choose a 12lb rifle over a 7lb rifle if they were used for the same thing? What about 9 vs 7? What's your limit? The way you talk about it, it sounds like you don't care what anything weighs, you're just going to simply "man up" and carry it, which is of course, ridiculous and lacks any logical thought process.
But I'll do my best to even give you an example, using something I did carry overseas and you referenced.
Daniel Defense 12.5" RIS 2 rail -- 17.7oz
SLR Solo 12.9" rail -- 9.9oz
Thats a 1/2lb difference just in the damn rail. When we got our DD uppers, one of the first things we noticed is how much heavier they felt than the previous uppers we had, even though barrel length was the same. While there were no "pussies" to be found, it was noticeable. Now factor in all the other shit we carried and it starts to matter.
This thought process applies to literally everything when it comes to gear and/or firearms. That same principle applies to backpacking, any hunting where you walk distances, competition, etc.
Why not optimize your ability by choosing a more logical approach if it fits your needs?