Yeah boas grow slow as paint dries. Gina has put maybe 6 inches since i got her 16 months ago. And he will for sure stay smaller than your retics for a MUCH longer time. I would be surprised if he broke 8 feet. Plus the other bonus is boas tend to not push or pace unless it gets hot out. Thats about the only time i see my boas getting antsy at the doors. I just slide one open and they usually will sit on the litter dam to cool off. Also boas dont eat nearly as much as retics or as often. Heck Rosey and Vicky eat a large rat once a month. Vicky sometimes gets a medium rat instead as I'm trying to slim her down a little since she got a little chub on her from eating all of Dotties refused rats lol.