I'm not sure the plant is E. spachiana. It looks unlike the ones I've seen. The spines are different and the branching behavior is different. But I wouldn't be able to offer any better ideas for the name. Maybe someone else with more experience would have one.
Anyway, a few thoughts based on my experience with a plant like the one pictured here:
This plant is a true survivor, if a bit of a messy grower. It's incredibly easy to start from cuttings, and the bottom part leftover (the "stump") will reliably branch after decapitation. It also tends to fall over once it reaches a certain height, unless supported by stems around it.
The plant in Bumpins' picture could be restarted from a short cutting (taken at the level of the top of the railing, for example) and that would make it easier to keep stable and move in for the winter.
If the goal is to move it intact to a bigger pot, I have some bad news. The original pot will most likely have to be broken in order to get the root ball out intact, because of the way it is shaped (the mouth being narrower than the part below). I'd take a hammer to the pot, carefully remove it from around the roots, and then move the plant to a pot maybe twice as wide (but not a whole lot deeper). The new pot must have a hole at the bottom. Keeping the plant upright will become an increasingly difficult challenge as it continues to grow.
Wrap a towel around the stem of the cactus in order to handle it safely, then remove the towel once it's in its new pot.
