"less clutter around your front"
Hmmm... not really, the long hose clipped to a D-ring is different from going across your chest, but can't see how it really counts as less clutter. Just different clutter.
"only one reg to worry about and thats in your mouth"
How is that different from mine? I only breathe the one in my mouth, other than when I check on the backup..
"Your breathing off a reg that would roll off in a overhead enviroment."
But (a) I rarely dive in an overhead, (b) I always check my backup DV after the valve takes any impact, © I don't think it's even possible to roll my valve off by it meeting the ceiling.
"Where is your back up reg ? (under your chin )why not use that "
Not according to your first post. Clipped to your D-ring, along with whatever else is clipped there.
"It will be you checked it when you do your checks before the dive, or did you forget."
That's still no guarantee. What if it rolled off as you backed out of the wreck? What if a bit of crud got in and jammed it or punctured the membrane? What if a hermit crab moved in while you weren't looking?
"Same goes for your rig you only breath off your right, your left could be off, so your rig is shite as well
"
But if it were off, I'd be wondering why my SPG still hadn't moved - you wouldn't. Unless it was off during the descent, in which case I'd wonder where the #### all my air had gone when I inflated my suit.
"would you die for your buddy
??"
No. But I wouldn't dive with a buddy I considered likely to kill me.
And under no circumstances would I refuse to give my buddy any help I could safely give. If my buddy goes OOA, he gets my DV. Even if it was his own fault for not monitoring his air.