Don't see why they couldn't stay in the growbag, the only thing stopping that may be that any rooted runners would overcrowd it a bit.
Pots are fine if they're big enough but don't see the point of moving them into small pots, if that was the thought.
Also, it wouldnt hurt to feed them now - normally the leaves on mine are sheared back after fruiting to tidy them up (but be careful not to chop the crowns, just cut the leaves) so trim the leaves and then give them a good feed and water so they produce some nice leafy growth before winter sets in. I shouldn't think they'd freeze solid on a roof terrace, but mind they don't get too waterlogged or too dry over winter.