I borrowed a Best Belt double prong from my gym for a year. Now got an Inzer single prong. I really think there's no extra stability from another prong, so it's just a personal preference. I find the single prong a tad easier to get on super tight. I'm a medium, got a large and it wouldn't survive a cut.
might as well. There's some studies that show there's no decrease in abdominal pressure when using a belt and there's actually more muscle activation in the glutes and quads with a belt on. Still good to develop a proper brace sequence sans belt though