I really think that it depends on the snake. I have 1000g snakes in 32qt tubs and some are very ready to move to bigger digs and some already have and are doing very well. I also have 1000g snakes who are just fine in 32qt tubs and so I will not move them.

As for breeding, I have my breeding females in 3x2x1 RBI cages as they are all over 1500g and in no way would be able to procreate with any sort of room- in my opinion.