Yusuf's Out of Bounds Adventures
http://www.youtube.com/watch?v=ANFIrB0BOTA
The results of messing around in sequence 2.
In the first memory I use the grab and drag/grab move/grab and move exploit. It's imperative that you do not skip the cinematic, since that will bring up the mission prompt, which will make Yusuf walk (there is no decline in the prompt). Also, watch it because it's awesome. 
When using the grab and drag/grab move/grab and move exploit, make sure to grab someone a bit further away from Yusuf in order to avoid interacting with Yusuf.
Despite Yusuf just having drowned, Ezio and he carry on a conversation like nothing's happened. I show that it's possible to get as far away from Yusuf as you want without desynchronizing. This isn't possible in the usual mission. However, it's impossible to finish the mission, since all but one of the events are triggered by Yusuf hitting a waypoint. Desynchronizing will get Yusuf back and allow you to finish the mission.
For the second memory, I perform the 'there is no stairs'-exploit on Yusuf, as well as a random assassin. Gentle push really is becoming AC:R's most deadly weapon! You can also try to punch Yusuf towards the stairs, but this is much harder to aim. About 100 metres is sufficient distance between Ezio and the stairs to make the latter disappear.
If you kill both "target assassins" with this exploit, you will be unable to finish the mission, unless you desynchronize, which will make Yusuf and the assassins reappear.
Hope you enjoyed the vid. 
It's great that grab-move still works (even better than in the previous games, haha). But I don't like the short distance you desynchronize from. 
And you can no longer to attempt to tackle characters that aren't meant to be tackled. Why?!
Because Ubi tried to fix some bugs. So many have been found! 
I know what you mean about the desync distance. I failed sequence 2 memory 7 like 3 times in a row because I was past the guards before Yusuf started walking. The warnings weren't even good. It was like: "Stay near your target" and then 0.5 seconds later: "Desynchronized".
I'm wondering about the minimum distance for a 'there is no stairs' desync. It appears to have been lowered a bit, since for the Yusuf kill in the vid, I moved about 120 metres. In your AC2 'there is no stairs' on Bernardo Baroncelli, you moved about 150 metres. It's about 200 metres in for the assassination variety pack Ian did for 'Wet Work'.
Since the mission expects you to brush up against him and let go of all buttons, I wouldn't say that a short desynch radius is unfair. : P
That has happened to me so many times in the AC series.
WARNI.....Desynch.
I refuse to let go of the controls. The camera angle is annoying.