Z1000 is by far the sickest bike i have ever owned. But for a stunter... Not so much. I also have an f4i that is my stunt bike. F4i is a good choice due to the strong frames, engines, and the endless amounts of parts that are availible.
There are quite a few downfalls of the Z when it comes to stunting. First and foremost, the 1 peice frame-subframe. Upon looping out a wheelie, the subframe takes the most impact. Having a 1 piece frame-subframe, you're looking at a lot more damage on even a normal drop while stunting. Also, in terms of stunt parts (crash cages, Handbrakes, dual caliper setups); there is a very small amount of parts for the z. I think 905 makes cages, but thats about it.
I will roll the occasional burnout down the street on my z, but i like my z too much to tear it up stunting it. Whenever i have the urge for wheelies, i just pull out the trusty ol' F4i and tear up the lot