Sounds like you are planning to break my browser's back functionality. If I were evaluating your site, you'd need to be pretty compelling to get to do that more than once.
There is a huge visual clue to the user that they are doing a "back" instead of a scroll (the whole page moves off to reveal the previous page behind it). It can be done accidentally, but a user will know what they have done and return. (In the static case, you have to move the page at least a quarter of the way out of the window. If you do a dynamic release it looks like less depending on how fast you are going. A "flick" could get you an accidental "back".)
Without looking at your site, I'll suggest that the bigger issue is that either "back"-"forward" isn't a no-op, or you leave a string of strange things in the back list. Both are common and both annoy users.
Not at all. The behavior in Lion (inverted scroll movement, bouncy scroll edges) encourages the user to see themselves as actually touching and directly manipulating physical objects on the screen (cf iPad/iPhone). One such resultant user-behavior is "flicking" to quickly perform the scrolling action.
If this behavior is overloaded with a navigational function, the user now may very well accidentally invoke the navigation function with a flick and lose data (HTML form data for example.)
This is a genuine usability issue that needs to be addressed by Apple.
The real world metaphor of flicking versus scrolling is quite obvious (you can move a paper on your desk, but flicking it will result in that paper not being there anymore).
Certainly, but the inertial scrolling on OSX actively encourages flicking as a mechanism to scroll a long distance. A genuine feature IMO.
…except, if you happen to be in a browser and at the far left or right of a page, then a big context switch suddenly occurs and navigational action is performed, potentially losing valuable state.
The use of two finger "flicking" is unnecessarily overloaded. Apple can solve this by making 3-finger navigation the default.
There is a huge visual clue to the user that they are doing a "back" instead of a scroll (the whole page moves off to reveal the previous page behind it). It can be done accidentally, but a user will know what they have done and return. (In the static case, you have to move the page at least a quarter of the way out of the window. If you do a dynamic release it looks like less depending on how fast you are going. A "flick" could get you an accidental "back".)
Without looking at your site, I'll suggest that the bigger issue is that either "back"-"forward" isn't a no-op, or you leave a string of strange things in the back list. Both are common and both annoy users.