There was a time when I moved ALL my gear to beltline or subloads; I was a) younger and less knowledgeable, and b) spending a lot of time behind a steering wheel that, if I'd put my gear on my chest, would have been rubbing my mags.
I think the concept of a subload is fine, but they have significant downsides (way more fatiguing, constantly changing position, etc.). If your gear is turning you into the Michelin man, and you need to have a gas mask too, I get it. For mags/pistol, I absolutely do not.
- Jake