I think the kings cage is fine. Nalani is in a 32x23x40 cage. She loves it!! At first, I got her a huge macaw cage, she didn't utilize half the space. It was bulky, heavy and honestly... a waste of money. So I downgraded her to a smaller cage. Now, she really enjoys it. She goes up in every corner to the floor. One thing I do have to watch is the placement of toys, number of toys and placement of perches. I make sure she has a lot of room to spread her wings, and move around in. (try hanging the toys on the side of the cage and on the perches, it utilizes more space aside from just the top cluster)
In my situation where Nalani is out for about 8 hours a day... it's ideal. She spends about 4 hours during the day and her "sleep" hours in her cage. So a huge cage is unnecessary. Think of it this way. If you plan on spending a lot of time with your bird outside of the cage, then a smaller cage is acceptable. But if you have work, school and other things in life, where your bird will be left in his/her cage most of the day. Then of course, bigger is better in that situation.