I've owned dozens of tanks ranging from 200 - 720 gallons with some being glass and some being acrylic and I still prefer acrylic on larger tanks for a few reasons:
My kid was playing with the magnet and scrated up a glass tank with a piece of crushed coral stuck to it and guess what that was the end of that tank.
A pice of LR tumbled and hit the side panel of a tank and put a little dimple in the glass which with time started running and I had to empty the tank and get the panel replaced a week later.
The LFS had a 600 gallon tank made out of 1" glass which cracked from the bottom due to the stand not being fully flat. Acrylic will actually bow allowing a certain amount of tolerance before breaking, unlike glass.
Acrylic is a better insulator, thus avoiding the temperature swings. This has been a big one for me since I live in Texas my house stays at 82F all day, then at night when I get home it get's pulled down to 74F, this normally always has caused problems in my glass tanks since the change in temperature is done so quick. My acrylic tanks insulate so well that it gives the heaters enough time to compensate for the slow temperature change (granted I could add alot more heaters to the glass tank), but same goes for heat I would require a big chiller with the glass tank.
I personally feel safer with an acrylic tank then a glass tank. I know if my kid bumps into it, nothing is going to happen since the panels have been welded in place and acrylic that thick can pretty much stop a low caliber bullet without breaking into a million pieces with the tank being empty that is.
The ownly downside to acrylic is that it scratches easy, this is true and coraline loves acrylic but, it's not a big problem to me. I use for the most part a Kent plastic blade to clean of the coraline.
I know some manufacturers now offer scratch free acrylic, but I don't know how this works. You may want to check with
http://www.aquartaquariums.com/ to see how this works.
One lass thing my 720 gallon tank which was 4FT tall was made out of 1" acrylic and weighed 850 lbs empty. I'm sure a glass tank that size would weigh in at over 1,500 lbs.
All in all if I didn't have kids coming over to the house and wouldn't upgrade tanks every 3 years I guess I would try a starphire tank, but honestly to the size and type of tank I'm moving to there is no way I would want a glass tank that is that tall and that big. Look at all the big systems (by big I mean 1000+ display size tank) there is a reason why they are all made out of acrylic.
