Interesting question, if you look at Yamada sensei's vid his ikkyo control is so good, what's the point of transitioning to nikkyo? If ikkyo is correct then nikkyo makes no sense as a transition.
For pure fun! [Its a better ending, alternative ending, etc.] I have control the whole time and can do either or, but prefer nikkyo ura just because.
[same reason I enjoy uchi-kaiten sankyo... and a bit less yankyo, though that can be cool too]