rimless tanks do use slightly thicker glass to compensate for the lack of trim support. however in your case, just because a rimless tank you found that appears to be similar does not mean its identical. granted its roughly the same size and uses the same thickness, but are you 100% sure it was the same material? and even at that, every manufacturer uses their interpretation of the perfect glass/ acrylic. that being said, that rimless manufacturer may be using glass that's designed for high stress (stronger). id personally recommend just leaving it alone. it may hold together at first, or even for a few months. but eventually, at some point, its prob going to fail. might happen when youre standing right in front of it, or it might happen when youre 3 hours away busy doing something.
as a tank failure victim, I can promise you that a tank failure is never something that you want to experience. 70 gallons may not seem like a lot, but drop a full glass of water on your floor and then multiply that by about 200 and that's what a tank failure is like.
