You are right, weight is in the corners. The bottom glass actually doesn't even touch the bottom of the stand, actually.
Yes, crappy particle board.
We bought a "heavy duty" stand that is supposed to hold 800lbs per shelf. My 15 gallon (let's say 170lbs) bowed the crappy particle board they give you. But the steel frame on it is pretty good, I'm sure THAT could hold the weight, but, particle board? Seriously, guys?
Ohh, ADA designs has glass intake tubes for canisters you can buy. I WANT. Really bad, but, uh, the whole "glass" thing terrifies me!