You won't kill it by cutting it back - nearly all azaleas respond well to even very radical pruning. What may happen, however, is that any new growth that appears in response to the cutting back will be winter killed. New growth at this time of year does not have enough time to harden off before winter sets in. In a very mild winter and/or protected location this may not happen. The decision to cut back further is entirely up to you. It's difficult to visualize from a two dimensional photo, at least for me, what a three dimensional plant will look like if replanted in a new location with a different orientation and exposure. Usually when moving something of this size, some growth needs to be cut away so you can get close enough to dig out the root ball. In any case, cutting back further or not cutting back further should have no effect on the azalea's survival. What is important is keeping it well-watered right up until the ground freezes.

You can always put the hole to the back when you replant it.

Other than trimming back what you need to do to get at the plant to dig it out, I'd save the rest of the pruning once it's planted in it's new location. It doesn't have to look rounded and full to look good. That's a misconception in my view.

Mike

great suggestions folks, thanks!

Current horticultural wisdom suggests that you NOT cut back any top growth before or immediately after transplanting. Leaving the top growth and as much foliage as possible intact helps the plant to re-establish in its new location. The roots need the foliage to remain in place to photosynthesize and nourish the root system and its presence actually reduces transplant shock. You double stress the plant and hinder establishment if you cut both the roots (inevitable when transplanting) and the top growth/leaves.