anyone ever had a problem? I never had any problems with size differences smallest poly i have is a 7" SB Delhezi and the largest is pushing past 24". And they're all kept together.
Realistically you don't want to have more than 2-3'' size difference. Polys can't help themselves...lol.... if it can fit in the mouth, it must be tasted and eaten!
I seperated mine because there is always one that is a bully or a mode change but to me it is always the lower jaws that have problems with each other.