What would you do about a backup mag in my situation?

Active Self Protection on YouTube says he's never seen a ccw holder do a mag change that mattered in the fight, and he's seen a ton of shootings. (If they even fired again it was all bad choices, like pot shots at the bad guy as he was running away.) So basically this means the rounds in the gun are the ones you got to fight with, and mag issues that can be addressed in time are a rarity.Now I have chronic back pain, and every ounce of firearm adds additional pain as the day goes along. Even though I always carry, my primary reason for carrying is to protect my children while we're out, mainly from someone taking them (a plausible threat in the area, and also from some estranged [and stalker] family members), so I don't wanna skimp on capacity. I currently 3:00 and find the balancing effect of a spare mag helpful. But due to weight loss I'll need to be switching to appendix soon for both comfort and concealment.If weight was as important to you as it is to me, would you consider not carrying an extra mag? Something like a G19/G17 (concealment ignored for the moment) would hold more rounds in the gun for immediate use than say a G26 does, but if I want a more reasonable weight I'd have to not carry a spare mag with a G19/17 sized gun. Similarly, you could also compare a G26 without a spare mag to a G43 with one.How unreliable are mags from the big manufacturers anyway? Can I buy a Glock/S&W/HK/CZ/etc. mag, shoot say 100 rounds through it, dedicate it solely to carry, and have confidence it won't fail me? via /r/CCW http://bit.ly/2Q78YeE