Hmmm, well I don't know about the quality of these.
My thought is that if you're going to put a bunch of expensive livestock into a glass box, spend the extra $450 and get a reputable brand over some second-tier manufacturer. It has to last a LOOOOONG time...
Glass aquariums are not held together by those silicone beads in the corners--the bulk of the joint strength actually comes from the millimeter or so of silicone that sits between the two pieces of glass. Precision is key here. If one piece of glass is not cut exactly right, or the joint is not perfectly square, or there is not consistent thickness in the silicone in the joint, or the joint surfaces are not properly cleaned and prepped--you get a weak joint.
If you're going glass, you want to make sure that the manufacturing process is controlled and proven. I wouldn't look for the cheapest box. I'd look for a box that is manufactured to standards that can be repeated, and make sure that quality is the rule, and not the exception.
That's my $0.02, FWIW.