Well there are actually two different types of Hybrids, there is the Green x Yellow and the Yellow x Green, and there is a difference. I'm not sure on how large the Yellow x Green Anacondas get, but I will say at least the size of a full grown Yellow Anaconda (males = 8-10', females = 10-12'). As far as the Green x Yellow Anacondas go, they have the same growth rate as a Green Anaconda and can get the same size (males = 10-12', females = 14-16'). I have seen about 8 Hybrids from the Green x Yellow Trait and actually owned one that was over 12', and they all had the same personality, mess with them, get musked and bit. I have only seen two Yellow x Green hybrids, and they were both babies, so I can't tell you on the temperment...
But in conclusion, these are not the best snakes to be getting involved with unless you know what you are doing.

Or any Anaconda for that matter.

Hope this helps some!
~Ben