Years ago, I grew Purple Majesty in a container for one year. It didn't seem to grow and bloom well for me. I wasn't impressed by the end of the season and didn't get it again. I had it by itself in a 20 inch container. Beautiful purple flowers.
I grow Amistad every year, as I'm very impressed with it every year. I have to get fresh plants of it, as it is not hardy for me.