Firstly, I am a glass guy, yes it is heavier, but doesn't scratch and I think glass gives a much brighter/cleaner look into the aquarium.
I had the same worries, had a 28G JBJ Nano, and built a custom 175G with 105G refugium. It has been up for 3 months now. I have it on the second floor of my house.
What you need to be concerned with is the bracing underneath. If possible try to figure out where the floor joices are, and what type they are. For example I have a newer house, so my joices are the squeekless type, so they don't use 2X4's of plain wood, they are glued layers of plywood and are much stronger than traditional. Also I put my tank in a spot where 3 to 4 joices ran underneath the the system and is also in the corner of the wall (2 supporting walls). What this meant is that I didn't have to brace the ceiling underneath the system (the garage, as the system is in a bonus room above the garage). My system is probably 2500-3000 pounds with no issues so far.
I hope this helps.