Bruce,
The year my brother hunted up there, the Big Bo was closed to hunting. We encountered a few hunters but none that interrupted our hunting. Only once did we find that another hunter was already hunting the bull we wanted to hunt. We backed off and hunted another bull. All in all, I wouldn't consider it crowded at all. My brother hunted the entire hunt and never had any problems with other hunters.
Think about it. I still say you should stick with unit 9, but that's just me. It's the best unit in the state if you truly are looking for the biggest bulls alive!!