Oh my goodness, oh my goodness I like that idea! Now the main reason for that top brace is to keep the tank from bowing, so if I did use that, would the bottom brace be necessary still?
I believe that the bottom has a brace because it's cheaper to make the piece with the brace than without.
Basically it's easier and cheaper to make 2 of the same piece than 2 different ones, so the bottom has the brace.
If you want to use the brace I linked to, note that there is a vertical component to it, so if you want to place glass flat against the top of the tank, you will not be able to do so. it would simply pivot around the brace.
But with all things, do your own research about how something will work; I haven't personally tried one of these so cannot vouch for how well it will work. To the best of my knowledge it will work without a problem, but you may want to try to find someone with first hand experience.