I went to a LFS and they had horror stories of the IM tanks, he was comparing the glass thickness to JBJ. But I went home and looked at mine, its just as thick. I think they may have fixed the issue on later production models, I do recall reading a thread on another forum of a guy having the crack issue and they sent him a replacement with thicker glass.
I have the Nuvo 30 and I like it, other than the fact that their own Ghost skimmer doesn't even fit properly in the god **** thing.