First thanks for such a great tool, been using it for more than a year now.
For me the biggest handicap continues to be the inability to capture scrolling windows properly. I've experience all of what has been mentioned here; screen flickering at a level where you panic and kill SC, to the latest "close but not enough". In fact yesterday was the first and only time I've got an actual screenshot of an scrolling window out of it, capturing this very same forum in Firefox. But as I said it has many flaws and it takes like 20 seconds of flickering and scrolling to come up with a picture. Check it out.
For me this is the only significant draw back compared to similar applications out there.
Is this issue in your road map of priorities mouser?