Yes, they definitely allow me to go a little heavier. They are way stouter than any bicycle shorts or under armor tights. Thick polyester, doubled at all the seems and like triple stitched. It's hard to say exactly how much they added, maybe 20 pounds? For me, they really support my hips/groin. The wider my stance, and the more I sat back, the better they worked. Also, if I pulled them up high really and cranked my belt down on them hard( I guess the way you're really supposed to do it?) they worked better. Tons of power out of the hole, added maybe 30-40 pounds? Perfect for overload.
They really support the hips and would help save wear and tear.
If you were narrow or moderate stance squatter you could block of training with wide stance to change things up. The briefs would really allow you to overload.
Louie says to wear briefs when you box squat.
I don't have much PL experience, and NO experience with real gear. I just recommended the Power Pants because they were cheap and easy to get on/off. Years ago someone on another board recommended I get some briefs to help after an adductor injury. I was looking at some expensive METAL briefs, when another guy suggested the power pants for like 1/3 the price. I was happy with them.
I know with a real suit you can go straps up or down, so maybe more long term versatility, but I've never put one on.