my background is rock crawling and i've had numerous belts and the topic comes up all the time. AND, my belts get USED all the time - upside-down, sideways, over backwards, etc.
from a RECREATIONAL stand point i have come to the conclusion that if belts are not comfortable or a pain in the butt to put on you won't use them and whats the point. second, the sub, or "crotch" belt is MOST important and it keeps the lap belts on your hips while allowing you to properly tighten the shoulders. If your lap belt rides on your belly internal injury is sure to happen - and once again, whats the point.
be realistic - my belly is just too big to comfortably wear a 3" belt ALL THE TIME, so whats the point. The addition of a breast buckle allows you to wear your shoulders just a little bit looser and still be relatively safe. Remember, if they aren't comfortable you won't wear them all the time and that's when things go bad. The breast buckle also REALLY helps when putting kids and smaller people in your vehicle as the shoulders belts won't fall off the shoulders.
So, I'll probably get "railed" on here as the new guy not knowing anything. Or saying they aren't ** approved or whatever. But this comes from first hand experience seeing injuries, and getting injured myself even when belts were available & not being used because they were a hassle or uncomfortable.
I have only been able to find these Simpson 2x2, w/pads, w/breast buckle, w/sub belt at the following link. PS. you have to call and ask for the breast buckle and maybe special order. They are in my rock crawler buggy & UTV and have kept myself, wife & kids safe many times - AND THEY ARE COMFORTABLE!
Simpson 2X2 Latch & Link Harness w/Pads - Black Rhino Performance