I have many hours teaching on both the T53 and the YS53
I have many hours teaching beginner private student on both the T53 and the YS53 and can say both aircraft did a fantastic job. But when they were both on the line sitting next to each other, flyer beware. Whatever you did, you shouldnt get them mixed up as their individual flight characteristic were quite different from one another once off the launch. The T53 that I used, had domed rivets and the YS53 didn't. Wow what a difference. I could never have imagined how much drag domed rivets would cause. Since that time, I have build several aircraft and every to I reached for a rivet I can't help but think of these two aircraft.
The other difference that could really catch a student out was the difference in rudder performance. The YS53 had an extension added to the top of the rudder that real made it a easier aircraft to get a balanced turn going if new to flying.
At this point my memory of these two is fading, but I have recollection the the control loads were also lighter on the YS53.
Believe it or not, I would aerobat both of them regularly.
I have some very fond memories of these two. Look, I have flown awful contraption and some very nice ones but for whatever reason these two got me into flying in a big way and made me smile. If I came across one at the right price, call me crazy but I may just need to get it for old time sake.
Have Fun