The Showtime is a better all around plane than the Quest. I am flying a Showtime now and had a Quest a year ago.
I flew my Quest with an OS 120, it flew good, but would be awesome with the YS 110.
I fly my Showtime with a Saito 150, but have seen one fly with the YS 110, and it flies very sweet, indeed.

Either of these planes will fly precise with the rates turned down, but the Showtime is a much better 3D machine on high rates.

My opinion, get the Showtime.

My .02.

Ken