Our new coach has the three camera system and I'm not a big fan for a few reasons. We typically tow a vehicle and I use the rear camera to see when my toad sufficiently passes the vehicle to my right before making a lane change. If I turn on my turn signal, which I like to do while making lane changes, you lose the ability to watch the toad and it's relationship to the vehicle your passing.
It may be just my cameras, but mine give a wide angle view which can be distracting when trying to determine if there is a vehicle and what lane it's in.
I also thought this system would work great while backing into a tight campsite. I would just turn on the turn signal on the side I wanted to see. Again, it may be my system, but in reverse, only the backup camera comes on and is not overridden by the turn signal. You need to go back to neutral to do so.
I almost upgraded my last coach to the three camera system because I thought it was a great feature. Now that I have it, I'm not a huge fan. I could live with or without it.
Just some thoughts for you to consider. If you could find a coach to test drive, you could see if you like the cameras or if they're distracting. I have the large Ramco mirrors where the lower third is a wide angle and they work great for monitoring side traffic.