I think cph is right.
If you remove all limitations and the size of your plant will be determined by the time/size she reaches in vegetation.
That is not to say a large pot will not improve yield or size.
The larger the root system the more hormones = bigger plant
IF it is not being limited by another bottleneck.
Think in bottlenecks
Thats just my take of things.
6 gallons are average size i believe?
I used a 55 liter sized pot filled with Coco - Its the largest ive dared and ive found that the potential size of the plants increases greatly.
Regardless , vegetation time is very long , the plants are near "immovable" throughout the whole operation, the management is hardwork , although large yields the system is inefficient in terms of g/w/m2.
Tree's are fun to grow though