I will say this about GC. From everything I have read and seen, they are really hit or miss. On one end you have the guy who just loves his/her tank and thinks it's the greatest thing since sliced bread. On the other end you have the guy/gal who's tank looked like a 3 year old put it together with 6X's to much silicone.
The owners are really hit or miss as well. I have called up there and talked to them and they seem as happy and nice as can be, and I have called up there and WOW it was like someone had urinated in their Corn Flakes.
Would I say that I would never buy from them, no. I am going to buy from them. I fully intend to get a 72"x24"x12" rimless grow-out tank from them and from that purchase I will be able to make a better personal opinion.
On a side note I did ask for a quote for my cube from them, via e-mail, and I'm still waiting to see what their quote is.