AusBonsai

i've had my Trident Maple in a Ceramic Bonsai pot for the last 6 months and it has grown around 1cm(if that), it's only around 6 inches tall(i'll edit this post with a picture soon)

what advantage would it get from using a Styrofoam "growing pot" as people call them here

Growth - simple as that. Even more if it went in the ground, but rather simply the smaller the root ball the less it will grow. Normally it only goes into a bonsai pot when the trunk and branches are the correct size. It can be common after a change in what you want from a tree to grow it on after removing it from a bonsai pot.

Tony