The problem with beer can chicken is the beer gets boiling hot (obviously), and the chook on top of it is unstable. When that mofo falls over and the boiling beer spills everywhere, it is a little inconvenient to say the least. Hence the sittin chicken, which is flared at the base, and much more stable.
For those with (charcoal) Webers, for sure you need to use the indirect method. The direct method would be far too hot. With a BGE, there's a ventilated ceramic plate between the coal & the grate, so it works as a smoker at the same time.
I've done dozens of these chickens. We got a new stove about 2 years ago. I don't believe it's seen a chicken. Much cleaner!