I don't think it would work as well in pots. I think the idea is that the tap roots go very deep and capture nutrients and trace minerals out of the reach of other plants.
I don't find it difficult to control at all. I've got Bocking 14 so it doesn't self seed. It's planted along the back of the shed and although it flops over a bit, it could be easily tidied up with a few canes and string. It's not really there long enough to be a problem. Like Growmore I take the shears to it as soon as it's looking like it needs cropping.
