mmh, looking at a similar model (I think):
It seems not that bad, it's quite 5s of time to max "zoom". Having not to change your lateral view, you keep looking the same angle, so you still continue seeing what happens. More, if I have a long distance courtyyard in that direction I could take a BI event motion, little far off, and get proper zoomed portion when it needs. Of course it's different if the subject moves laterally.
In my case I think it's doable...
Anyway, apart the speed problems, is it doable inside BI and how specifically?