Hey Mike, just found your thread. Great looking tank. What are the dimensions of the display tank? (sorry if I missed that in your posts) What are your plans for aquascaping?
I like your idea for the return manifolds. Ever thought of using a couple sea-swirls or wavy-seas for the center return manifold instead of the static loc-line? I realize that you will have the OM's on the two end manifolds, but couldn't hurt to maximize random turbulence/currents. Dunno, just a thought. I would, especially if you're planning to keep sps.
Just one other quick thought; I know someone else already commented on this and you said that the pool balls are locked away and no kids, but as far as the pool table being so close to the tank, man that would scare the heck out of me. Dunno about you, but I see balls fly off of pool tables even with adults/good players. Maybe you could build a shield of some sort made out of plywood on a base with wheels that you could roll in front of the tank when playing pool?
Great job though! Keep the pictures of the progress comin'!