i have done this but by examining the root mass after harvesting i don not think i would do it again, i was told but a professor in one of my botany classes to go around the outside of the rootball on the edge of the
smart pot and drive the shovel in around and along the edge of ur smartpot then peel it down like peeling a banana. i tend to do this when root mass has dried out a bit so the mass stays together then after tp i water the hell out of them with soluble kelp and dyna grow silica amendment so as to reduce shock, ive also used house and gardens root excelurator for a week after tp, so as to boost root production. i have put a smartpot in another smartpot but then you have 2 smartpots in use as opposed to one, as i run perpetually this is a bad idea because 2x's increases overhead cost and thus reduces profit margiin. dont get me wrong it will work just not sure of the benefits. i should also mention since i switched to air pots i will never go back to smarties!! i run smarts up to the final tp then they go in the big airpots and i freekin love em!! twice the plant out of half the soil.