I haven't tried the 'up the bum chicken' on the grill - I usually just grill the cut-up chicken. But I've had chicken cooked that way in the oven, a friend of my sister (who's run a restaurant and is a fantastic cook) fixes it that way and it was quite good.
So, ordered a sittin' chicken and I'll be trying it. Perhaps a 'side by side' - fixing one on the sittin' chicken on the grill, and one in the smoker and doing a taste test