The SPIBelt will flop if you have too much weight loaded in a single pocket. They have them with 2 belts so you can spread the stuff out. And also it helps to keep it very tight.
The thing I don’t like about the flipbelts is putting them on and taking them off. You have to slide your whole body into and out of it. Not sure if they have come up with one with a fastener.
Another thing about the flipbelts is that they are not adjustable - at least the ones I have are not. So if you gain or lose weight, or carry more or less stuff, it’s basically the same diameter.
I have 2 flipbelts, a million SPIBelts (with pockets ranging from 1 to 3), and a whole lot of other assorted pockets and pouches and belts for carrying, including waterproof belts for rain, etc. Having a bunch of different ones makes it easier to just select what I need. It’s always different.