Autogyrating? False Walls, and shot unarmed...
"s it plausible that the helis were doing a high rate-of-decent landing that might have been somewhat quieter than a standard landing, possibly even auto-rotating?"
I posited that same theoriy/supposition but it wasn't bought. It appears the story is that they fast-roped in. But, I think that fastroping means they have to concentrate on firing in all directions without causing friendly fire to themselves or the helo. It also means they have to avoid roping down too hard and breaking a leg and ending up dead. I presume the helo landed fast and hard and offered shelter from incoming non-RPG fire until they would bolt for the compound.
Also, it seems that OBL never played Half-Life, Counter Strike, or the like. Nor did he, apparently, watch any Vietnam War related movies. Hamburger Hill, one soldier runs and falls into a stake pit, with 7 or 8 of them piercing him. No hope for rescue or recovery. But, a pit with only a FEW stakes and which has delated fuse would take out the initailly trapped as well as the rescuer.
All those false walls are pointless if they don't ensare or disable or take out the entrant. Anyone laying paint that is detectable only by one's specifically-tuned night optics will be able to backtrack out of and avoid reentering dead ends.
Half Life is known for campers. Those with severe lag end up having no choice but to camp and lay satchel bombs and trip mines. That way, the uninitiated get a taste of their own medicine before the player with laggy and crappy graphics blacks out and respawns.
He fought and killed assymetrically, yet, neither he nor his guards apparently learned from playing Wester FPS games.... Major fail...