I doubt its the cage. Like i said, others i have seen with GC have shed issues too. Maybe its because the other guys' GC has tiger in it? Snakes dont need a lot of room to shed. My 7 foot and 6 foot boas are able to shed in 1 piece inside their hides lol. They roll it up like a sock.
But as for tubs, i personally hate them lol. What's the point in having the snake if you dont have it displayed in a nice big glass or acrylic fronted cage. From a breeders standpoint, i can see the uses but from a pet keeper, if you dont have the room or are too cheap to buy a nice cage, then dont buy the snake. Thats just my feeling. Sorry for the rant lol.