We'd like to use 5/16" BR-111 Santos Mahogany instead of 7/16" because we don't want the heigth difference to be another 1/8" over our existing floor. Aside from the obvious (more ability to sand the thicker product), is there any other reason to choose the thicker wood. I know the thicker product is also slightly narrower.

The 5/16 and the 7/16 are virtually identical you will be happy with either. I prefer the 5/16 because you can get the wider widths.

That's great news since it's cheaper, I wanted the smaller depth, and, most importantly, that's what my wife wanted!