Originally posted by First Poster Hard to resist but hard to justify too.
The way I see it, this is a wildlife lens with secondary applications to airshows, airports (for commercial aircraft watchers, where the approach pattern is predictable and the size and weight aren't the sort of issue they are when aerobatics and low fast passes are happening) and so on. If that's the sort of shooting you're already doing regularly, that's justification enough - all you need is the money (and yes, that price is very good).
On the other hand, if you've got the money and you have to consciously think about what you might use the lens for... no. To me that's a sign you need to reconsider. Save it, or spend it on other lenses/gear that would improve the shooting you're already doing.
Then again, if perchance you're lucky enough to be the sort of person for whom $1600 is pocket change... why not?