Flow sits at the top of my "most annoying web app ever" list, because it follows the pattern of loading an empty shell, then populating it. I bet this works amazingly well for the guys developing it from their local dev server, but for those of us across the Atlantic from your servers it's really really painful.
Workflow involves clicking a link to look at a task. Then hitting the back button. Then waiting several seconds for the list to slowly repopulate itself. Then trying to scroll down (which is no easy feat since there's no scroll bar), and just before you get back to where you wanted to be, the list jumps back to the top. Repeat (scroll/jump/scroll/jump) several times before the page settles down, usually cutting the last item in half with no way to see it.
So yeah, Step One: HTML in a table. So that the back button works, and the page otherwise behaves like a web page.
Step two: Un-reinvent the scrollbar. The javascript thing you have in place that only works with the mousewheel just plain doesn't work.
Glad to see you're doing well for yourselves, but I'm sorry to report that I'm one of the people in your "churn" column.