140lbs sounds pretty good, and I wouldn't mess much with your aquascape by pilling on more rock - it looks really good! Maybe a shelf piesce or two to create some shade for less light tolerant specimens in the future?

Your filtration may be a little light as the bio-load increaes, but probably OK for now. The addition of a Fuge or more LR in a sump, or a Wet/Dry, or some combination of all of these is worth considering ... and let's you keep "improving" your system ... it is a hobby after all :-D

On the 2" vs. 1" - Unless you have a HUGE volume of water, 1" standpipes should be fine. The downside to 2" is any plumbing (Elbows, etc.) require more physical space. Also 2" PVC requires a hacksaw or other method to cut whereas 1" and smaller can be cut with a ratcheting PVC cutter which is much easier. If you have two standpipes, you may want to consider using 1" on the standpipes, but increase to 1.5" or 2" in the plumbing where they join together before dumping into the sump? This would give some future increase capacity when you add your second and third tanks to your system :-D :-D

Enjoy - looks great!