Answer: In my experience moving a burning bush shrub of this size will be very difficult. If nothing else the root system will be huge and extremely heavy. Roots usually spread out substantially wider than the branches -- and this is a deep rooted shrub as well. It is unlikely you will be able to dig up all of the roots, so there will be some unavoidable rootloss. This has to be compensated for by the shrub dieing back, or by pruning off some of the branches.
I think professional equipment such as a tree spade would be more disruptive than helpful in such a small workspace area -- be prepared with a sturdy tarp to set it on to drag it to the new location, or a sheet of plywood with rollers under it.
It will take it several years to recover from being moved so it reestablishes and begins to grow well again -- the larger and older the plant, the longer this process can take. Ideally you would prepare it ahead of time by root pruning; this develops a network of roots closer to the plant and makes it easier to dig with an intact rootball thus reducing the chances of dieback. Here is some information on how to do that if you want to try it. You would root prune this fall to move it in early spring.
It occurs to me it might be easier to add two shrubs, one close to the steps on one side and one 10 feet out on the other and then hard or renewal prune the existing shrubs in late winter to scale them down in size. Eventually the new ones would catch up and you would ahve a set of four.
Good luck with your project!
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