Main problem I see with infinite scrolling is that it is simply impossible to scroll by dragging scrollbar, as once you get near the end of page it shrinks and

Main problem I see with infinite scrolling is that it is simply impossible to scroll by dragging scrollbar, as once you get near the end of page it shrinks and jumps around. Combined with arrow keys repurposed for something else than scrolling (G+) and PageUp/PageDown scrolling by slightly more than viewport (because of fixed elements on top/bottom) it makes some sites highly unusable without scroll wheel (which reasonable laptops does not have :)).