Neal, nice! Looking good. The layout will be great. Is that an AIU in the first pic? I've never felt the need for one on either layout. Love to hear how you like it.
You've seen my double-tracked, 8 X 10's, with the 1 1/2 inch clearance to the edge. In five years, the only way anything fell was when I was talking instead of looking and one train caught up to the other on the same track. Being O gauge, there are numerous derailments, especially in the first year. Since then, all those little track issues have been resolved. BTW, after falling six feet to a very hard tile floor, the only things that have ever broken were those cheap plastic trucks on the old Lionel stuff from the 80's. Haven't had one in years, but, I was amazed the cars themselves always survive completely intact.
Your trains look great up there. The CP holiday train is always cool to see. Have you considered a backdrop to hide the brackets?
Keep them coming, it's fun to see the progress.