These frames are similar. To me, the 300T is a bit more plush and comfortable, with slightly more touch, feel and maneuverability. But, it's very low powered. IMO, the touch, feel and low power is due in large part to the 18x20 string pattern which means you have to tension way down due to the 300T's moderate weight, or the result will be boardy. If you lead it up, you can string it a little tighter.
The PSGT is slightly lighter overall, but, has a bit more pop, especially in the upper hoop which is a bit dead on the 300T. I think this is because the shape of the PSGT is broader across the top, and it's balanced heavier in the head than the 300T which gives it a bit more plow.